Chemistry Test - 5

The monomers used in the preparation of dextron are lactic acid and glycolic acid. There action for the formation of dexron can be written as

Group 15 elements acts as Lewis base in - 3 oxidation state due to availability of lone pair of electrons on the central atom. This basic character of group 15 decreases down the group with an increase in the size of the central atom.

Nitrogen doesn’t react with concentrated sulphuric acid as its bond dissociating energy is highest among the given elements. This is because of its small size.

Chemical formula for manganate and permanganate ion respectively are MnO^2-₄ and MnO^-₄ . Thus, the ionic charge of manganate and permanganate ion are respectively -2 and -1.

The enzyme which converts maltose to glucose is maltase. During digestion, starch is partially transformed into maltose by pancreatic or salivary enzymes called amylases; maltase secreted by the intestine men converts maltose into glucose. The glucose so produced is either utilised by the body or stored in the liver as glycogen.

The chemical formula for aluminium phosphate is AIPO₄ .

Atomicity of heteronuclear molecule = total number of atoms present

∴ Atomicity of AlPO₄ = 1 +1 + 4 = 6

Standard hydrogen electrode (SHE) is the primary reference electrode. SHE is represented by Pt(s)|B₂ (g)|H⁺ (ag), is assigned a zero potential at all temperatures corresponding to reaction.

Key idea: Isotonic solutions are those solutions which have the same osmotic pressure at a given temperature.

Formula for osmotic pressure, π = CRT

considering the set given in option (d), i.e. 30 gL^-1 urea and 17.1 gL^-1 sucrose.

Given, the molecular mass of urea 60 g mol^-1 and molecular mass of sucrose 342 g mol^-1 .

For urea.

conc, C = 3/60 = 1/20

Osmotic pressure π₁ = (1/20) x R x T

For sucrose conc, C = 17.1/342 = 1/20

∴ Osmotic pressure, π₂ = (1/20) RT

Thus, the set of solutions of urea and sucrose given in option (d) is isotonic.

Natural polymers are those polymers which are found in plants and animals. Among the given polymers liner is a natural polymer which is made from cellulose (polymer of glucose molecules).

When a mixture of manganese dioxide, potassium hydroxide and potassium chlorate is fused then potassium chlorate first decomposes to give potassium chloride and oxygen gas. The formed O₂ gas then reacts with MnO₂ and KOH to give K₂ MnO₄ . The equations for the above reaction can be written as

2MnO₂ + 4KOH + O₂ → 2K₂ MnO₂ + 2H₂ O

Relationship between van't Hoff factor(i) and degree of dissociation (α) is given by

α = 1-i/n'-1

where, n is the number of ions formed alter dissociation.

The relationship can be obtained as follows;

For the reaction, A ⇌ n'B

Initially 1 mole 0

After dissociation (1 - α) mole n' α

Total number of moles present in the solution

= (1 - α) + n'α = 1 + (n'-1)α

van't Hoff factor, i = 1 + (n' - 1), α > 1 if n' ≥ 2

∴ α = i-1/n'-1

For there action,

Iodide ion acts a homogenous catalyst as the phase of I^- and reactant, H₂ O₂ is aqueous (same).

The Wortz reaction between methyl chloride and sodium metal in presence of dry ether can be written as

⇒ 2 moles of sodium metal reacts to give 1 mole of ethane.

Also,

1 mole of Na metal = 23 g

∴ 2 motesol Na metal = 23x 2 = 46g

Thus, 46 g of sodium is required to prepare one mole of ethane from methyl chloride by Wurtz reaction.

C(s) + O₂ (g) → CO₂ (g), ΔH₁ = -X, …(i)

CO(g) + (1/2)O₂ (g) → CO₂ (g), ΔH₂ = -Y, ….(ii)

For the formation of CO subtract Eqs. (ii) from (i), i.e,

∴ Δ_r H for formation of CO = ΔH₁ - ΔH₂

= -x+y or y-x

Acetic acid is obtained when ethanenitrile is acid hydrolysed. The equation for the reaction can be written as

The total vapour pressure of a solution in this case only depends on vapour pressure of water as anhydrous oxalic acid is a non-vola tile compound.

∴ Vapour pressure of solution = vapour pressure of water (p_w )

According to Raoutt’s law p_w = x_w pº_w

Number of moles of oxalic acid = 9/90 = 0.1 moles

∴ x_w = 9.9/9.9+0.1 = 0.99

⇒ p_s = p_w = 0.99 x pº₁