Question

1. (a) Two elements represented by the letters Q and R have atomic numbers 9 and 12 respectively.

(i) Write the election configuration of R.
(ii) To what group does Q belong in the periodic table.
(iii) Write the formula of the compound formed when Q combines with R.
(iv) Explain briefly, why Q is a good oxidizing agent.
(v) State whether R would be expected to form acidic or basic oxide.
(b) (i) State two assumptions of the kinetic theory of gases.
(ii) When some solids are heated, they change directly into the gaseous state. What name is given
to this phenomenon?
(iii) List two substances which exhibit the phenomenon mentioned in (ii).
(iv) Write an expression to show the mathematical relationship between the rate of diffusion of a
gas and its vapour.
2. An aqueous solution has a pH of 4.0.

Answer 1

This answer addresses the electron configuration of element R, the group of element Q, the formula of the compound formed when Q combines with R, why Q is a good oxidizing agent, whether R would form an acidic or basic oxide, assumptions of the kinetic theory of gases, the name of the phenomenon in which solids change directly into the gaseous state when heated, two substances that exhibit this phenomenon, and the mathematical relationship between the rate of diffusion of a gas and its vapor.

Step-by-step explanation:

(a) Two elements represented by the letters Q and R have atomic numbers 9 and 12 respectively.

(i) The electron configuration of R is 1s2 2s2 2px2 2py1 2pz0 3s2 3px2 3py0 3pz0.

(ii) Q belongs to Group 17 (Group VIIA), which is the Halogens group.

(iii) The formula of the compound formed when Q combines with R is QR2.

(iv) Q is a good oxidizing agent because it has a high tendency to gain electrons and can easily accept electrons from other elements or compounds.

(v) R would be expected to form a basic oxide.

(b)

(i) Two assumptions of the kinetic theory of gases are: (1) Gases consist of a large number of small particles that are in constant random motion, and (2) The volume occupied by the gas particles is negligible compared to the total volume of the gas.

(ii) The phenomenon of solids changing directly into the gaseous state when heated is called sublimation.

(iii) Two substances that exhibit sublimation are iodine and dry ice (solid carbon dioxide).

(iv) The mathematical relationship between the rate of diffusion of a gas and its vapor is described by Graham's law, which states that the rate of diffusion of a gas is inversely proportional to the square root of its molar mass.

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