Which of the following statements is true of the periodic table?

• A. It is based on nucleon number.

• B. The elements are divided into five blocks.

• C. There are eight groups in the periodic table.

• D. There are seven periods in the periodic table.

The proton numbers of chlorine, potassium and calcium are given below.

CI = 17, K = 19, & Ca = 20

Thus, we can conclude that the ionic radii of CI^-, K⁺ and Ca²⁺ ions increase in the order of

• A. CI^- < K⁺ < Ca²⁺

• B. Ca²⁺< K⁺ < CI^-

• C. K⁺ < Ca²⁺< CI^-

• D. K⁺ < CI^- < Ca²⁺

The following pairs of elements are in Period 3 of the periodic table. Which of these pairs has the greatest difference in boiling points?

• A. Silicon and aluminium

• B. Sodium and aluminium

• C. Silicon and phosphorus

• D. Aluminium and phosphorus

In which of the following pairs does the first species have a larger size?

• A. N, P

• B. P^3-, P

• C. Mg, Na

• D. Mg²⁺, Mg

Which of the following elements has the highest second ionisation energy?

• A. Iron

• B. Silicon

• C. Magnesium

• D. Sodium

The successive ionisation energies of an element are given below.

760 (first). 1540, 3300, 4399, 8950, and 119000 kj mol^-1

• A. Is a d-block element.

• B. Is a p-block element.

• C. Is a s-block element.

• D. Has half-filled p orbitals.

On moving across Period 3 (from sodium to chlorine)

• A. The oxides of the elements become more acidic

• B. The electronegativity of the elements decreases

• C. The first ionisation energy of the elements decreases

• D. The strength of the elements as an oxidising agent decreases

Which of the following statements is true about fluorine?

• A. Energy is absorbed when fluorine atoms gain electrons to form fluoride ions.

• B. Fluorine is less electronegative than chlorine.

• C. The first ionisation energy of fluorine is higher than oxygen.

• D. The atomic radius of fluorine is larger than that chlorine.

The electronic configuration of the four elements are shown below:

R: 1s² 2s² 2p⁶ 3s¹

X: 1s² 2s² 2p⁶ 3s² 3p⁶

Y: 1s² 2s² 2p⁶ 3s² 3p⁴

Z: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²

Which of the elements form basic oxide?

• A. Element R and Y

• B. Element R and Z

• C. Element X and Y

• D. Element Y and Z

The electronic configuration of element Q is shown below:

1s² 2s² 2p⁶ 3s² 3p⁶ 4s²

Which of the following statements is of Q?

• A. It is located in Period 4.

• B. It is Group II element.

• C. It has a low melting point.

• D. It is a poor electrical conductor.