PART - 1 CH - 2 Structure of Atom — Chemistry STD 11 Science — Question

Give general characters of elements of s, p, d and f-block.

Calculate the degree of ionization of 0.05M acetic acid if its pK_a value is 4.74. How is the degree of dissociation affected when its solution also contains (a) 0.01M (b) 0.1M in HCl?

The concentration of sulphide ion in 0.1M HCl solution saturated with hydrogen sulphide is 1.0 × 10^–19M. If 10mL of this is added to 5mL of 0.04M solution of the following: FeSO₄, MnCl₂, ZnCl₂ and CdCl₂. in which of these solutions precipitation will take place?

Give reasons for the following:

1. Covalent bonds are directional bonds while ionic bonds are non- directional.
2. Water molecule has bent structure whereas carbon dioxide molecule is linear.
3. Ethyne molecule is linear.

Distinguish between a sigma and a pi bond.

A sample of 0.50g of an organic compound was treated according to Kjeldahl’s method. The ammonia evolved was absorbed in 50ml of 0.5M H₂SO₄. The residual acid required 60mL of 0.5M solution of NaOH for neutralisation. Find the percentage composition of nitrogen in the compound.

Perform the following calculations and express the results to proper number of significant figures.

1. 144.3 m² + (2.54 m × 8.4 m).
2. (4.05 × 10²mL) - (0.0225 × 10²mL).
3. (3.50 × 10²cm) (4.00 × 10⁶cm).

What is the concentration of sugar (C₁₂H₂₂O₁₁) in mol L^–1 if its 20g are dissolved in enough water to make a final volume up to 2L?

What transition in the hydrogen spectrum would have the same wavelength as the Balmer transition n = 4 to n = 2 of He⁺ spectrum?