MODULE 3 PART 1.5

Question Number. 41. Surface molecular attraction between two different molecules is.
Option A. adhesive.
Option B. gravitational.
Option C. cohesive.
Correct Answer is. adhesive.
Explanation. Cohesion is the property that causes like substances to cling together (e.g. water molecules, forming raindrops - from 'cohesion' meaning to stick together). Adhesion is the property that causes unlike substances to stick together (e.g. the raindrops stick, or 'adhere to' a washing line).




Question Number. 42. The atomic mass number is the number of.
Option A. protons plus electrons.
Option B. neutrons plus electrons.
Option C. protons plus neutrons.
Correct Answer is. protons plus neutrons.
Explanation. Mass Number is the number of protons + neutrons.




Question Number. 43. A catalyst in a chemical reaction does what?.
Option A. Can either speed it up or slow it down.
Option B. Speeds it up.
Option C. Slows it down.
Correct Answer is. Speeds it up.
Explanation. Official definition of 'catalyst': A substance that increases the rate of a chemical reaction by reducing the activation energy, but which is left unchanged by the reaction.




Question Number. 44. What is the number of electrons in the inner-most shell of an atom?.
Option A. 4.
Option B. 8.
Option C. 2.
Correct Answer is. 2.
Explanation. The inner shell of an atom has 2 electrons.




Question Number. 45. What form of heat is used to turn a solid into a gas?.
Option A. Sensible heat.
Option B. Specific heat.
Option C. Latent heat.
Correct Answer is. Latent heat.
Explanation. To change any state, the heat required is called 'latent heat'.




Question Number. 46. The heat required to change a liquid to a gas at constant temperature is the heat of.
Option A. fusion.
Option B. condensation.
Option C. vaporisation.
Correct Answer is. vaporisation.
Explanation. The heat required to turn a liquid into a gas (vaporise) is called the 'latent heat of vaporisation'.




Question Number. 47. An atom with a full outer shell is.
Option A. practically inert.
Option B. a good insulator.
Option C. a good conductor.
Correct Answer is. practically inert.
Explanation. An atom with a full outer shell is practically inert.




Question Number. 48. An element with a full valence shell is.
Option A. very reactive.
Option B. good conductor.
Option C. inert.
Correct Answer is. inert.
Explanation. An element with a full valence shell is inert.




Question Number. 49. A substance of two or more different atoms is.
Option A. a neutrino.
Option B. an isotope.
Option C. a chemical compound.
Correct Answer is. a chemical compound.
Explanation. A compound is two or more different atoms.




Question Number. 50. An atom with 5 electrons in its outer shell is.
Option A. trivalent.
Option B. pentavelent.
Option C. covalent.
Correct Answer is. trivalent.
Explanation. Valency is the number of electrons in the outer shell (up to 4) or 8 minus the number of electrons in the outer shell (over 4).