Why should a magnesium ribbon be cleaned before burning in air?

A solution of potassium bromide is mixed with a solution of lead nitrate. What will be the observation, and what type of reaction is it?

Which type of reaction involves the breakdown of a single compound into two or more simpler substances?

How do you test for the presence of hydrogen gas?

What is the balanced equation for the reaction of hydrogen gas with chlorine gas to form hydrogen chloride gas?

If a student heats a blue crystalline solid, it turns white, and water droplets are observed on the cooler parts of the test tube. What is the blue crystalline solid?

In the reaction: FeSO4(aq) + Cu(s) → No reaction. Why does this happen?

Which gas is released when dilute hydrochloric acid reacts with calcium carbonate?

Explain why an iron gate needs to be painted regularly.

What are the reactants required for the process of photosynthesis?

Which of the following is an example of a precipitate forming reaction?

Consider the reaction: 2SO2(g) + O2(g) → 2SO3(g). If this reaction is carried out at high temperature and pressure, how would it affect the rate of reaction?

What is the common term for a reaction that involves both oxidation and reduction simultaneously?

Identify the reaction where electricity is used to break down a compound.

Why are antioxidants added to food items containing fats and oils?

A white solid on heating produces a gas that turns limewater milky and a residue that is yellow when hot but white when cold. Identify the white solid.

Which type of reaction is the thermite reaction (Fe2O3 + 2Al → Al2O3 + 2Fe)?

Assertion (A): Rusting of iron is a fast process. Reason (R): Rusting requires specific conditions of air and moisture to occur.

Balance the equation: C6H12O6 + O2 → CO2 + H2O. What is the coefficient of O2?

Why is a black coating formed on the surface of some utensils exposed to a gas flame for a long time?

What is the general name for a reaction that releases energy, often in the form of heat or light?

In the reaction: Fe2O3 + 2Al → Al2O3 + 2Fe. Which element is acting as the reducing agent?

Give a reason why balanced chemical equations are important for industrial processes.

What type of chemical reaction is involved in the digestion of food?

When a student observed that a certain metal tarnished over time, forming a green layer, what could be the metal?

Which of the following reactions is an example of electrolytic decomposition?

Why does food cook faster in a pressure cooker? Relate it to chemical reactions.

Assertion (A): White silver chloride turns grey in sunlight. Reason (R): Decomposition of silver chloride in the presence of sunlight forms silver metal and chlorine gas.

What is the purpose of adding iron filings to a solution of copper sulphate in a laboratory experiment?

A reaction is represented as A + B → C + D. If A and B are reactants, and C and D are products, what must be true about the total mass of A and B compared to C and D?

What is the term for a substance that slows down the rate of rancidity?

When a student mixes solutions of copper sulphate and iron filings, what change would be observed over time?

Consider the reaction: Zinc + Hydrochloric Acid → Zinc Chloride + Hydrogen. Is this a redox reaction? Justify your answer.

Why is it dangerous to add water to concentrated acid rapidly?

Balance the following chemical equation: Fe + H2O → Fe3O4 + H2. What is the sum of the coefficients of the reactants?

Which of the following substances will show a color change when heated strongly, and what is the color change?

Why is solid calcium oxide stored in airtight containers?

What type of reaction occurs when an acid reacts with a base?

Identify the reducing agent in the following reaction: CuO + H2 → Cu + H2O.

A student performs an experiment where he adds dilute sulphuric acid to barium chloride solution. What visual change will he observe?

How is the phenomenon of 'corrosion' different from 'rancidity'?

Balance the equation: Al + H2SO4 → Al2(SO4)3 + H2. What is the coefficient of H2SO4?

Which of the following indicates that a chemical reaction has taken place?

Give an example of a reaction where a gas is evolved and a change in temperature is observed.

Why are decomposition reactions generally endothermic?

A student observes bubbles forming when a dilute acid is added to a metal sample. What gas is most likely being produced?

Assertion (A): Photosynthesis is considered an endothermic reaction. Reason (R): Energy is absorbed from sunlight during photosynthesis.

What is the general term for a reaction in which a more reactive metal displaces a less reactive metal from its salt solution?

When solid lead nitrate is heated, it decomposes. Name the gas(es) evolved that have a reddish-brown colour.

Identify the reaction type: A + Oxygen → AO (e.g., C + O2 → CO2).

What is meant by rancidity and how can it be prevented?

Write the balanced chemical equation for the reaction of sodium with water.

Why does the color of copper sulphate solution change when an aluminium foil is dipped in it?

Which type of reaction is characterized by the exchange of ions between two compounds?

Give one example of a combination reaction that is also exothermic.

What is indicated by the symbol (aq) next to a chemical formula in an equation?

A solution of sodium carbonate is added to a solution of barium chloride. Which of the following observations is true?

Which of the following metals would displace hydrogen from dilute acids?

What is the role of a catalyst in a chemical reaction?

Assertion (A): Oxidation involves the loss of electrons. Reason (R): Reduction involves the gain of electrons.

***New Question Draft (replacing the problematic one):*** When 10g of calcium carbonate is heated, it decomposes to calcium oxide and carbon dioxide. If 5.6g of calcium oxide is formed, what mass of carbon dioxide is produced?

Consider the reaction: AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq). If 10g of AgNO3 reacts completely with NaCl, and 8.5g of NaNO3 is formed along with AgCl. What is the mass of AgCl formed?

What are the conditions necessary for rusting to occur?

A solution turns blue litmus red. It reacts with zinc metal to evolve a gas that burns with a 'pop' sound. What type of substance is the solution?

Why is it important to balance chemical equations?

When magnesium ribbon is burnt in air, a white powder is formed. What is the chemical name of this powder?

Consider the reaction: 2Pb(NO3)2(s) --(Heat)--> 2PbO(s) + 4NO2(g) + O2(g). What type of reaction is this?

Balance the following chemical equation: (NH4)2Cr2O7 → N2 + Cr2O3 + H2O. What is the sum of the stoichiometric coefficients of the products?

What observation helps to distinguish between a physical change and a chemical change in a reaction?

Identify the type of reaction when an aqueous solution of iron(III) chloride is mixed with an aqueous solution of ammonium hydroxide.

During the electrolysis of water, if 20 mL of hydrogen gas is collected at one electrode, what volume of oxygen gas will be collected at the other electrode under the same conditions?

A solution of substance X is used for whitewashing. The substance X is formed by the reaction of water with what?

Which of the following reactions is used for the preparation of oxygen in the laboratory?

Why is respiration considered an exothermic reaction?

What is the significance of the arrow pointing downwards (↓) in a chemical equation?

In the reaction represented by the equation: MnO2 + 4HCl → MnCl2 + 2H2O + Cl2. Identify the oxidizing agent.

A student dropped a few pieces of marble in dilute hydrochloric acid contained in a test tube. The gas evolved was passed through limewater. What changes would be observed in the limewater?

Which of the following is an example of a redox reaction?

What happens when an iron nail is dipped in a copper sulphate solution?

Assertion (A): Calcium carbonate decomposes into calcium oxide and carbon dioxide when heated. Reason (R): The decomposition reaction requires energy in the form of heat.

When hydrogen gas is passed over heated copper(II) oxide, a black substance, it turns reddish-brown. Write the balanced chemical equation for this reaction and identify the substance reduced.

A shiny brown element X on heating in air becomes black. Name the element X and the black-coloured compound formed.

Which of the following processes involves a chemical reaction?

Why are silver articles found to turn black when exposed to air for a prolonged period?

Consider the following reaction: A + B → C + Heat. What can be inferred about this reaction?

A student places a piece of copper wire in a test tube containing silver nitrate solution. After some time, the solution turns bluish, and a shiny gray solid deposits on the copper wire. i) Write the balanced chemical equation for the reaction. ii) Identify the oxidizing agent and the reducing agent in this reaction.

How does painting prevent corrosion?

Consider the reaction: CH4(g) + 2O2(g) → CO2(g) + 2H2O(l). i) Is this reaction exothermic or endothermic? Justify your answer. ii) What type of reaction is this?

What are the two main types of corrosion? Give an example of each.

Which of the following metals would react most vigorously with dilute hydrochloric acid?

Explain why reduction and oxidation always occur simultaneously in a chemical reaction.

A white solid, when strongly heated, melts and then decomposes to produce a brownish gas and a residue that is yellow when hot and white when cold. Identify the white solid.

Why is the reaction between hydrogen gas and chlorine gas to form hydrogen chloride gas considered a combination reaction?

During a laboratory experiment, a student mixes two colorless solutions, X and Y. Immediately, a blue precipitate forms. What could be X and Y?

What is the significance of the state symbols (s), (l), (g), and (aq) in a balanced chemical equation?

Consider the reaction: 2Pb(NO3)2(s) → 2PbO(s) + 4NO2(g) + O2(g). If this reaction is carried out in a sealed container, what observation might violate the Law of Conservation of Mass if the container was not sealed?

Why are decomposition reactions typically endothermic?

When a few drops of phenolphthalein indicator are added to a solution of sodium carbonate, the solution turns pink. What will happen if dilute hydrochloric acid is added drop by drop to this solution?

Which of the following is an example of a single displacement reaction?

A student performs an experiment where he mixes an aqueous solution of Barium Chloride with an aqueous solution of Sodium Sulphate. i) What is the immediate observation? ii) Write the balanced chemical equation for the reaction. iii) What type of reaction is this?

Distinguish between an oxidizing agent and a reducing agent in terms of electron transfer.

During the electrolysis of water, if the volume of hydrogen collected is 10 mL, what will be the volume of oxygen collected at the same conditions?

A chemist tests two unknown white powders. Powder A, when heated, produces a gas that rekindles a glowing splint. Powder B, when heated, produces a gas that turns limewater milky. Identify Powder A and Powder B.

When a student burns a piece of magnesium ribbon in a jar of oxygen, a white powder is formed. If this white powder is then dissolved in water and a drop of red litmus paper is added, what color change will be observed and why?

State one difference between displacement and double displacement reactions.

Which of the following compounds is a strong oxidizing agent often used in redox titrations?

How can you demonstrate experimentally that the reaction of hydrogen and oxygen to form water is a combination reaction?

Describe the role of oxygen in both corrosion and rancidity.

What is the color change observed when ferrous sulphate crystals are heated?

Why is it necessary to balance a chemical equation? Explain with reference to a fundamental law.

Predict the product(s) of the following reaction and identify the type of reaction: Al(s) + HCl(aq) →

Which of the following reagents can be used to distinguish between magnesium oxide and calcium oxide?

A student observed that when dilute hydrochloric acid was added to a piece of magnesium ribbon, the temperature of the test tube increased. What type of reaction is this?

Why are certain types of chemical reactions, like photosynthesis and thermal decomposition, considered endothermic?

An aqueous solution of metal nitrate P reacts with sodium bromide solution to form a yellow precipitate of compound Q which is used in photography. Q on exposure to sunlight undergoes decomposition to form a metal R and a reddish-brown gas. Identify P, Q, and R.

What is the role of manganese dioxide (MnO2) in the decomposition of potassium chlorate (KClO3)?

Give an example of a reaction that is both a combination reaction and an exothermic reaction.

A student wanted to store fresh potato chips for a long time. What method should they use to prevent them from becoming rancid?

Which of the following observations indicates that a chemical reaction has taken place?

When silver chloride is exposed to sunlight, it decomposes to form silver metal and chlorine gas. i) Write the balanced chemical equation for this reaction. ii) What type of reaction is this? iii) What is the commercial application of this reaction?

Consider the reaction: Fe2O3(s) + 2Al(s) → Al2O3(s) + 2Fe(s). Which of the following statements about this reaction is incorrect?

A student observed that on mixing solutions of two salts, a precipitate was formed. What are the common characteristics of such reactions?

Which of the following is a balanced equation?

Why is photosynthesis considered an endothermic reaction?

In the decomposition of lead nitrate powder, what is the color of the gas evolved and the residue left?

A student noted that a strip of aluminum metal was placed in a beaker containing a solution of copper chloride. After some time, the blue color of the solution faded, and a reddish-brown deposit was observed on the aluminum strip. What is the reason for this observation?

Which of the following reactions is used for the preparation of oxygen?

Define a redox reaction. Give one example.

Why are chips manufacturers flush bags of chips with nitrogen gas?

Consider the reaction: CuO(s) + H2(g) → Cu(s) + H2O(l). Identify the substance undergoing reduction.

When a zinc granule is added to a test tube containing dilute sulphuric acid, a gas is evolved. What is the gas, and how would you test for it?

Which of the following is not a characteristic of a chemical reaction?

Balance the following chemical equation: KMnO4 + HCl → KCl + MnCl2 + H2O + Cl2

In an experiment, when a student added a few drops of universal indicator to a solution of sodium hydroxide, the color changed to blue. What kind of reaction would occur if hydrochloric acid was then slowly added to this solution?

Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.

Which of the following statements about the given reaction are correct? 3Fe(s) + 4H2O(g) → Fe3O4(s) + 4H2(g) (i) Iron metal is rusting. (ii) Water is getting reduced. (iii) Water is acting as a reducing agent. (iv) Iron is getting oxidized.

A solution of a substance 'X' is used for whitewashing. i) Name the substance 'X' and write its formula. ii) Write the reaction of the substance 'X' with water.

Identify the substance oxidized in the following reaction: ZnO + C → Zn + CO

Why does a brown layer form on iron articles when left exposed to air and moisture for some time?

A student dropped a small piece of marble into a test tube containing dilute hydrochloric acid. A gas evolved which turned lime water milky. What type of reaction occurred?

Which of the following is an exothermic process?

Explain why iron articles are often painted.

When hydrogen sulphide gas is passed through a blue solution of copper sulphate, a black precipitate of copper sulphide is formed and sulphuric acid is formed. The reaction is an example of:

Which of the following processes involves a chemical change?

A shiny brown element X on heating in air becomes black. Name the element X and the black-colored compound formed.

When a student mixes solution A (containing lead(II) nitrate) with solution B (containing potassium iodide), a yellow precipitate forms. What type of chemical reaction is this, and write the balanced chemical equation?

What do you mean by a precipitation reaction? Explain by giving examples.

In the refining of silver, the recovery of silver from silver nitrate solution involved displacement by copper metal. Write down the reaction involved.

What is the difference between displacement and double displacement reactions? Write equations for these reactions.

Write one equation each for decomposition reactions where energy is supplied in the form of heat, light or electricity.

Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions

Why is respiration considered an exothermic reaction? Explain

What does one mean by exothermic and endothermic reactions? Give examples.

What is a balanced chemical equation? Why should chemical equations be balanced?

What happens when dilute hydrochloric acid is added to iron fillings? Tick the correct answer. (a) Hydrogen gas and iron chloride are produced. (b) Chlorine gas and iron hydroxide are produced. (c) No reaction takes place. (d) Iron salt and water are produced

Fe₂O₃ + 2Al → Al₂O₃ + 2Fe The above reaction is an example of a (a) combination reaction. (b) double displacement reaction. (c) decomposition reaction. (d) displacement reaction.

Identify the substances that are oxidised and the substances that are reduced in the following reactions. (i) 4Na(s) + O2(g) → 2Na2O(s) (ii) CuO(s) + H2(g) → Cu(s) + H2O(l)

Why does the colour of copper sulphate solution change when an iron nail is dipped in it?

A solution of a substance ‘X’ is used for whitewashing. (i) Name the substance ‘X’ and write its formula. (ii) Write the reaction of the substance ‘X’ named in (i) above with water.

Write a balanced chemical equation with state symbols for the following reactions. (i) Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride. (ii) Sodium hydroxide solution (in water) reacts with hydrochloric acid solution (in water) to produce sodium chloride solution and water

Write the balanced equation for the following chemical reactions. (i) Hydrogen + Chlorine → Hydrogen chloride (ii) Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride (iii) Sodium + Water → Sodium hydroxide + Hydrogen

A solution of substance ‘X’ is used for white washing. What is the substance ‘X’? State the chemical reaction of ‘X’ with water.

Hydrogen being a highly inflammable gas and oxygen being a supporter of combustion, yet water which is a compound made up of hydrogen and oxygen is used to extinguish fire. Why?

What is meant by a chemical reaction?

1 g of copper powder was taken in a China dish and heated. What change takes place on heating? When hydrogen gas is passed over this heated substance, a visible change is seen in it. Give the chemical equations of reactions, the name and the colour of the products formed in each case.

Oil and fat containing food items are flushed with nitrogen. Why?

A shiny brown coloured element ‘X’ on heating in air becomes black in colour. Name the element ‘X’ and the black coloured compound formed.