MODULE 3 PART 1.3

Question Number. 21. What form of heat is used to turn a solid into a liquid?.
Option A. specific heat.
Option B. coefficient of heat.
Option C. heat of fusion.
Correct Answer is. heat of fusion.
Explanation. Fusion' is another term for melting (as in fusion welding).




Question Number. 22. Change from solid to gas state without going through liquid state is called.
Option A. transformation.
Option B. sublimation.
Option C. state leap.
Correct Answer is. sublimation.
Explanation. Sublimation is when a solid vapourises without first melting.




Question Number. 23. What is the smallest particle of matter that can exist in nature?.
Option A. A molecule.
Option B. An isotope.
Option C. An atom.
Correct Answer is. An atom.
Explanation. An atom is the smallest particle of matter that can exist in nature.




Question Number. 24. A positive ion.
Option A. has extra electrons.
Option B. has missing electrons.
Option C. is a radioactive isotope.
Correct Answer is. has missing electrons.
Explanation. A positive ion is an atom with missing electrons.




Question Number. 25. The isotope of a carbon atom C14 to C12 will have.
Option A. same numbers of neutrons.
Option B. same numbers of protons.
Option C. same number of electrons.
Correct Answer is. same numbers of protons.
Explanation. An isotope is an atom with the same atomic number but different mass number. Atomic number is the number of protons. Mass number is the number of protons plus neutrons. Note: the number of electrons can differ from one atom to another (making ions).




Question Number. 26. If an atom has 2 protons, how many electrons will it have?.
Option A. 1.
Option B. 8.
Option C. 2.
Correct Answer is. 2.
Explanation. Since it is an 'atom' (and not an ion) it has the same number of electrons as protons.




Question Number. 27. A molecule with like atoms is said to be a.
Option A. neutroid.
Option B. compound.
Option C. element.
Correct Answer is. element.
Explanation. If only one type of atom is involved, it is an element.




Question Number. 28. Two elements in the same substance is said to be a.
Option A. mixture.
Option B. element.
Option C. compound.
Correct Answer is. compound.
Explanation. A compound is a substance formed by chemical reaction between 2 or more elements. A mixture could be 2 or more compounds. A tenuous question.




Question Number. 29. The number of protons in an atom is equal to the number of.
Option A. electrons.
Option B. neutrons.
Option C. mass number.
Correct Answer is. electrons.
Explanation. No. of protons = No. of electrons, or it is not an atom.




Question Number. 30. The charge of an electron is.
Option A. neutral.
Option B. negative.
Option C. positive.
Correct Answer is. negative.
Explanation. Electrons are negative.