Post Utme Chemistry Past Questions and Answers

Question 36:

The number of atoms in one mole of a substance is equal to ____________

A. The atomic number
B. The Avogadro's number
C. Number of neutrons
D. Number of electrons
E. Gas constant

Question 37:

The number of electrons in the outermost shell of the atom represents its ____________

A. Period
B. Number of shells
C. Group
D. Atomic number
E. Electronegativity

Question 38:

The number of protons or electrons of an atom represents its ____________

A. Electronegativity
B. Period
C. Number of shells
D. Group
E. Atomic number

Question 39:

The partial pressure of oxygen in a sample of air is \(500 \mathrm{mmHg}\). If the total Pr pressure 780 \(\mathrm{mmHg}\), what is the mole fraction of the oxygen?

A. \(0.64\)
B. \(5.73\)
C. \(1.56\)
D. \(0.70\)
E. \(0.54\)

Question 40:

The furring of kettles is caused by the presence in water of ____________

A. Calcium trioxocarbonate (IV)
B. Calcium tetraoxosulphate (VI)
C. Calcium hydroxide
D. Calcium hydrogentrioxocarbonate (IV)