- AA match burning creates ash, so mass is lost.
- BWater evaporating creates steam, so mass is lost.
- CWhen iron rusts, its mass increases because it combines with oxygen.
- DAn ice cube melting does not change its mass.
More Questions on Atoms AND Molecules
Which of the following is an example of an ionic compound?
→ 2Which of the following is a polyatomic molecule of an element?
→ 3What is the chemical formula for glucose?
→ 4What is the chemical symbol for Barium?
→ 5The total number of protons and neutrons in an atom is called the:
→ 6Which of these is generally more reactive?
→ 7What is the chemical symbol for Silicon?
→ 8The formula for hydrogen peroxide is H2O2. How many total atoms are in one molecule?
→ 9Which part of the atom determines its identity as a specific element?
→ 10Which of these represents an element?
→ 11What is the chemical symbol for Bromine?
→ 12The smallest particle of matter that can exist independently and retain all the properties of that substance is a:
→ 13If two atoms share electrons, they form a:
→ 14What makes different elements unique from each other?
→ 15Which element has the chemical symbol 'I'?
→ 16How many different elements are present in the compound H2SO4?
→ 17Which of the following is a representation of an atom?
→ 18The atomic theory suggests that atoms are mostly:
→ 19What is the chemical symbol for Fluorine?
→ 20Which element has the chemical symbol K?
→ 21In a chemical reaction, atoms are:
→ 22The formula for quicklime is CaO. What does it represent?
→ 23Which particle's number defines an element?
→ 24Which of the following is true about a compound?
→ 25What is the total number of atoms in one molecule of methane (CH4)?
→ 26The chemical properties of an atom are determined by the number of:
→ 27Which of these is a homogeneous mixture?
→ 28What is the chemical formula for common baking soda (Sodium Bicarbonate)?
→ 29The symbol 'Sn' represents which element?
→ 30What is the primary difference between an atom and an ion?
→ 31A compound must contain at least:
→ 32Which is the correct chemical symbol for Helium?
→ 33A molecule of ozone has how many oxygen atoms?
→ 34What is the chemical formula for Calcium Carbonate (limestone)?
→ 35If a sample contains only gold atoms (Au), it is considered:
→ 36Which of the following correctly represents a molecule of an element?
→ 37An element always consists of:
→ 38When wood burns, the atoms of wood are:
→ 39The symbol 'Mg' represents which element?
→ 40Which subatomic particle is involved in forming chemical bonds between atoms?
→ 41The most reactive metals often form:
→ 42Which model of the atom describes electrons orbiting the nucleus like planets around the sun?
→ 43If an atom loses an electron, its overall charge becomes:
→ 44In the formula 2H2O, the number '2' before H2O signifies:
→ 45Which of these is a mixture?
→ 46A substance composed of two or more elements chemically combined in a fixed ratio is a:
→ 47How many atoms are in one molecule of ammonia (NH3)?
→ 48What is the chemical formula for Carbon Monoxide?
→ 49The symbol 'Ne' represents which element?
→ 50Which of the following is a chemical formula?
→ 51If a substance contains only one type of atom, it is called an:
→ 52Dalton's atomic theory helped to explain the:
→ 53The atomic number identifies an element because it represents the number of:
→ 54What are the components of a solution?
→ 55Which of these is NOT a pure substance?
→ 56The chemical symbol 'Al' stands for:
→ 57The formula C6H12O6 represents a molecule of glucose. How many carbon atoms are there?
→ 58Which state of matter has particles that are widely separated and move randomly and rapidly?
→ 59Which state of matter has particles that are most tightly packed and vibrate in fixed positions?
→ 60When ice melts into water, what happens to its molecules?
→ 61If you have a block of pure gold, what are the smallest particles present?
→ 62An atom of Nitrogen and an atom of Oxygen combining to form a molecule of Nitrogen Monoxide (NO) is an example of:
→ 63What is the chemical symbol for Zinc?
→ 64What is the chemical symbol for Copper?
→ 65What is the chemical symbol for Sulphur?
→ 66What is the chemical symbol for Phosphorus?
→ 67What is the chemical symbol for Nitrogen?
→ 68Which of the following statements is true about molecules?
→ 69In a neutral atom, the number of electrons is equal to the number of:
→ 70The atomic mass of an atom is primarily determined by the sum of its:
→ 71Which subatomic particle is the lightest?
→ 72What is the chemical symbol for Chlorine?
→ 73What is the chemical symbol for Calcium?
→ 74The symbol 'Hg' represents which element?
→ 75The symbol 'Pb' represents which element?
→ 76Which of these is a pure substance made up of two or more different types of atoms chemically bonded together?
→ 77Which of these is a pure substance made up of only one type of atom?
→ 78The chemical formula for sulphuric acid is H2SO4. How many oxygen atoms are in one molecule?
→ 79How many atoms in total are present in one molecule of water (H2O)?
→ 80How many different types of atoms are present in a molecule of water (H2O)?
→ 81Which of these represents a compound?
→ 82What is the chemical formula for common salt?
→ 83A negatively charged ion is formed when an atom:
→ 84A positively charged ion is formed when an atom:
→ 85An atom that has gained or lost electrons is called an:
→ 86Which of the following is a neutral particle in an atom?
→ 87When wood burns, ash is formed. The total mass of ash and gases produced is equal to:
→ 88The Law of Conservation of Mass states that:
→ 89Which of these is an example of a diatomic molecule?
→ 90What is the chemical symbol for Gold?
→ 91What is the chemical symbol for Silver?
→ 92What is the chemical symbol for Potassium?
→ 93What is the chemical symbol for Sodium?
→ 94Which of the following elements has the chemical symbol Fe?
→ 95The smallest unit of a compound that retains the chemical properties of that compound is a:
→ 96According to Dalton's atomic theory, atoms of the same element are:
→ 97Which scientist proposed the atomic theory that states atoms are indivisible particles?
→ 98What does the formula CO2 represent?
→ 99What does the formula H2O represent?
→ 100What is the chemical symbol for Carbon?
→ 101What is the chemical symbol for Hydrogen?
→ 102What is the chemical symbol for Oxygen?
→ 103Which of these is a molecule of a compound?
→ 104Which of these is a molecule of an element?
→ 105What is a molecule?
→ 106The number of protons in an atom is known as its:
→ 107What charge does a neutron carry?
→ 108What charge does a proton carry?
→ 109Which two subatomic particles are found inside the nucleus of an atom?
→ 110What is the center part of an atom called?
→ 111Which subatomic particle carries a negative charge?
→ 112What is the fundamental building block of all matter?
→ 113How many atoms are present in H₂SO₄?
→ 114Name a diatomic gas.
→ 115Calculate formula unit mass of CaCl₂.
→ 116How many atoms are there in exactly 12 g of carbon?
→ 117Give Latin names for sodium & mercury.
→ 118What is molecular mass?
→ 119What name is given to the number 6.023 × 10²³?
→ 120What term is used to represent the mass of 1 mole molecules of a substance?
→ 121Who gave law of conservation of mass?
→ 122Give one relevant reason why scientists chose 1/16 of the mass of an atom of naturally occurring oxygen as the atomic mass unit.
→ 123What is the atomicity of Argon?
→ 124What are polyatomic ions? Give two examples.
→ 125What is the number of electrons in Mg atom and Mg²⁺ ion?
→ 126‘Atoms of most elements are not able to exist independently.’ Name two atoms which exist as independent atoms.
→ 127Name the element which is used as the reference for atomic mass.
→ 128Which organisation approves the names of elements all over the world ? Write the symbol of gold.
→ 129Define law of constant proportion.
→ 130Define law of conservation of mass.
→ 131Name the scientist who laid the foundation of chemical sciences. How?
→ 132Calculate the molar mass of the following substances: (a) Ethyne, C₂H₂ (b) Sulphur molecule, S₈ (c) Phosphorus molecule, P₄ (Atomic mass of phosphorus = 31) (d) Hydrochloric acid, HCl (e) Nitric acid, HNO₃
→ 133Give the names of the elements present in the following compounds: (a) Quick lime (b) Hydrogen bromide (c) Baking powder (d) Potassium sulphate
→ 134Write the chemical formulae of the following: (a) Magnesium chloride (b) Calcium oxide (c) Copper nitrate (d) Aluminium chloride (e) Calcium carbonate
→ 135What are polyatomic ions? Give examples.
→ 136When 3.0 g of carbon is burnt in 8.00 g of oxygen, 11.00 g of carbon dioxide is produced. What mass of carbon dioxide will be formed when 3.00 g of carbon is burnt in 50.00 g of oxygen? Which law of chemical combination will govern your answer?
→ 137A 0.24 g sample of a compound of oxygen and boron was found by analysis to contain 0.096 g of boron and 0.144 g of oxygen. Calculate the percentage composition of the compound by weight.
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