Atomic Basics

Question Who postulated the idea of 'Parmanu'? tap to flip ↻ Answer Maharishi Kanad Question What does the word 'atom' mean? tap to flip ↻ Answer Indivisible Question Who proposed the atomic theory in 1808? tap to flip ↻ Answer John Dalton Question State the Law of Conservation of Mass. tap to flip ↻ Answer Mass can neither be created nor destroyed in a chemical reaction. Question State the Law of Constant Proportions. tap to flip ↻ Answer In a chemical substance, elements are always present in definite proportions by mass. Question What is the ratio of masses of hydrogen to oxygen in water? tap to flip ↻ Answer 1:8 Question What is the ratio of masses of nitrogen to hydrogen in ammonia? tap to flip ↻ Answer 14:3 Question What is the atomic radius unit? tap to flip ↻ Answer Nanometre (nm) Question Who suggested that symbols of elements be made from one or two letters? tap to flip ↻ Answer Berzilius Question What is the symbol for iron? tap to flip ↻ Answer Fe Question What is the symbol for sodium? tap to flip ↻ Answer Na Question What is the symbol for potassium? tap to flip ↻ Answer K Question Define atomic mass unit (u). tap to flip ↻ Answer One atomic mass unit is exactly one-twelfth the mass of one atom of carbon-12. Question What is the atomic mass of hydrogen? tap to flip ↻ Answer 1 u Question What is the atomic mass of oxygen? tap to flip ↻ Answer 16 u Question What is a molecule? tap to flip ↻ Answer A group of two or more atoms chemically bonded together; smallest particle capable of independent existence. Question What is atomicity? tap to flip ↻ Answer The number of atoms constituting a molecule. Question What is the atomicity of oxygen? tap to flip ↻ Answer Diatomic Question What is the atomicity of phosphorus? tap to flip ↻ Answer Tetra-atomic Question What is an ion? tap to flip ↻ Answer A charged species; may be a single atom or a group of atoms with a net charge. Question What is an anion? tap to flip ↻ Answer A negatively charged ion. Question What is a cation? tap to flip ↻ Answer A positively charged ion. Question What is a polyatomic ion? tap to flip ↻ Answer A group of atoms carrying a charge. Question What is valency? tap to flip ↻ Answer The combining power (or capacity) of an element. Question Write the formula for hydrogen chloride. tap to flip ↻ Answer HCl Question Write the formula for hydrogen sulphide. tap to flip ↻ Answer H2S Question Write the formula for magnesium chloride. tap to flip ↻ Answer MgCl2 Question Write the formula for aluminium oxide. tap to flip ↻ Answer Al2O3 Question Write the formula for calcium hydroxide. tap to flip ↻ Answer Ca(OH)2 Question Write the formula for sodium carbonate. tap to flip ↻ Answer Na2CO3 Question Write the formula for ammonium sulphate. tap to flip ↻ Answer (NH4)2SO4 Question What is molecular mass? tap to flip ↻ Answer The sum of the atomic masses of all atoms in a molecule. Question Calculate the molecular mass of water (H2O). tap to flip ↻ Answer 18 u Question Calculate the molecular mass of HNO3. tap to flip ↻ Answer 63 u Question What is formula unit mass? tap to flip ↻ Answer The sum of the atomic masses of all atoms in a formula unit of a compound. Question Calculate the formula unit mass of NaCl. tap to flip ↻ Answer 58.5 u Question Calculate the formula unit mass of CaCl2. tap to flip ↻ Answer 111 u Question Which postulate of Dalton's theory explains the law of conservation of mass? tap to flip ↻ Answer Atoms are indivisible and cannot be created or destroyed in a chemical reaction. Question Which postulate of Dalton's theory explains the law of definite proportions? tap to flip ↻ Answer Atoms combine in the ratio of small whole numbers to form compounds. Question What is the chemical formula of a compound? tap to flip ↻ Answer A symbolic representation of its composition.