MODULE 3 PART 1.4

Question Number. 31. A valance electron is an electron.
Option A. in the innermost shell.
Option B. in the outermost shell.
Option C. which is not within an atom.
Correct Answer is. in the outermost shell.
Explanation. The outer shell is the valence shell.




Question Number. 32. Molecules of unlike atoms are combined by their.
Option A. adhesive force.
Option B. magnetic force.
Option C. cohesive force.
Correct Answer is. adhesive force.
Explanation. Cohesion is the property that causes like substances to cling together (eg water molecules, forming raindrops - from 'cohesion' meaning to stick together). Adhesion is the property that causes unlike substances to stick together (eg the raindrops stick, or 'adhere to' a washing line).




Question Number. 33. What is the difference between hydrogen, deuterium and tritium?.
Option A. The number of electrons.
Option B. The number of protons.
Option C. The number of neutrons.
Correct Answer is. The number of neutrons.
Explanation. There are three isotopes of the element hydrogen: hydrogen, deuterium, and tritium. They each have one single proton (Z=1), but differ in the number of their neutrons. Hydrogen has no neutron, deuterium has one, and tritium has two neutrons.




Question Number. 34. The smallest material in the universe is.
Option A. an ion.
Option B. helium.
Option C. hydrogen.
Correct Answer is. hydrogen.
Explanation. Hydrogen is the smallest known element, having just 1 electron and 1 proton and no neutrons.




Question Number. 35. What is the atomic number of the element shown here?.
Option A. 7.
Option B. 3.
Option C. 4.
Correct Answer is. 3.
Explanation. The atomic number is the number of protons and is always the smallest number (and yes, the element shown is not possible).




Question Number. 36. What is the mass number of the element shown here?.
Option A. 4.
Option B. 5.
Option C. 9.
Correct Answer is. 5.
Explanation. The mass number is the number of protons + the number of neutrons and is always the biggest of the 2 numbers.




Question Number. 37. There are solids, liquids and gases present in the universe and every unit of theirs occupy some space. This is called.
Option A. matter.
Option B. compound.
Option C. mass.
Correct Answer is. matter.
Explanation. All material in space is known as matter. (All matter 'has' mass, but that is not what the question asks - what is it known as, not, what does it have).




Question Number. 38. An atom deficient of a valency electron is deficient.
Option A. of an electron in the outer shell.
Option B. of a neutron in the outer shell.
Option C. of an electron in the inner shell.
Correct Answer is. of an electron in the outer shell.
Explanation. The valency electrons are in the outer shell.




Question Number. 39. The maximum number of electrons in the second shell is.
Option A. 4.
Option B. 8.
Option C. 2.
Correct Answer is. 8.
Explanation. Try the formula '2n-squared', where 'n' is the shell number. In this case 2 * (2 * 2) = 8.




Question Number. 40. What does an oxygen atom consist of?.
Option A. Protons, neutrons and electrons.
Option B. Protons and electrons.
Option C. Protons and neutrons.
Correct Answer is. Protons, neutrons and electrons.
Explanation. All atoms have protons, neutrons and electrons (except hydrogen, which has no neutrons).