The maximum prescribed concentration of cadmium in drinking water in ppm is

• 0.05

• 3

• 2

• 0.005

A 100% pure sample of a divalent metal carbonate weighing 2 g on complete thermal decomposition releases 448 cc of carbon dioxide at STP. The equivalent mass of the metal is

• 40

• 20

• 28

• 12

The ratio of the frequency corresponding to the third line in Lyman series of hydrogen atomic spectrum to that of the first line in Balmer series of Li²⁺ spectrum is

• $\frac{4}{3}$

• $\frac{3}{4}$

Among the following, the molecule of highest dipole moment is

• CCl₄

• NH₃

• H₂O

• CHCl₃

The incorrectly matched pair, among the following is-

• BrF₅ - Trigonal bipyramidal

• SF₄ - See-saw

• ClF₃ - T-shape

• NH₃ - Trigonal pyramidal

The gas with the highest critical temperature is

• CO₂

• He

• N₂

• O₂

Molecules/ ions and their magnetic properties are given below-

Molecule/ Ion	Magnetic Property
i. C6H6	1. Antiferromagnetic
ii. CrO2	2. Ferrimagentic
iii. MnO	3. Ferromagnetic
iv. Fe3O4	4. Paramagnetic
v. Fe3+	5. Diamagnetic

The correctly matched pairs in the above is

• i - 5; ii - 3; iii - 2; iv - 1; v - 4

• i - 3; ii - 5; iii - 1; iv - 4; v - 2

• i - 5; ii - 3; iii - 1; iv - 2; v - 4

• i - 5; ii - 3; iii - 1; iv - 4; v - 2

Among the following, the element of highest first ionisation enthalpy is

• C

• Ne

• Be

• N

Which one of the following has the shortest bond length?

• C - H

• C - N

• C - F

• C - C

20.

Choose the weak monobasic acid, among the following

• H₃BO₃

• H₃PO₃

• H₃PO₄

• HNO₃