HSC Science (Computer Science) इयत्ता १२ वी - Maharashtra State Board Question Bank Solutions for Chemistry

Write the molecular and structural formulae of Dithionous acid

Write chemical reaction to prepare the following polymer: Teflon

The standard enthalpy of combustion of formaldehyde Δ₀H⁰ = -571 kJ. How much heat will be evolved in the formation of 22 g of CO₂?

Pyrolusite ore is _______.

A 0.1 m solution of K₂SO₄ in water has a freezing point of –4.3°C. What is the value of van’t Hoff factor if K_f for water is 1.86 K kg mol^–1?

Answer the following in one or two sentences.

What is van’t Hoff factor?

Answer the following in one or two sentences.

How is van’t Hoff factor related to degree of ionization?

Answer the following in one or two sentences.

Which of the following solution will have higher freezing point depression and why?

i. 0.1 m NaCl

ii. 0.05 m Al₂(SO₄)₃

Answer the following in one or two sentences.

Which of the four colligative properties is most often used for molecular mass determination? Why?

Derive the relationship between the degree of dissociation of an electrolyte and van’t Hoff factor.

At 25 °C, a 0.1 molal solution of CH₃COOH is 1.35 % dissociated in an aqueous solution. Calculate the freezing point and osmotic pressure of the solution assuming molality and molarity to be identical.

A 0.15 m aqueous solution of KCl freezes at - 0.510 °C. Calculate i and osmotic pressure at 0 °C. Assume the volume of solution equal to that of water.

In which of the following, entropy of the system decreases?

Answer the following in one or two sentences.

State whether ΔS is positive, negative or zero for the reaction 2H_(g)  →  H_2(g). Explain.

Answer the following in one or two sentences.

State second law of thermodynamics in terms of entropy.

Answer the following in one or two sentences.

If the enthalpy change of a reaction is ∆H how will you calculate the entropy of surroundings?

Answer the following in one or two sentences.

Comment on the spontaneity of reactions for which ∆H is positive and ∆S is negative.

Obtain the relationship between ∆G° of a reaction and the equilibrium constant.

Answer in brief.

What is entropy? Give its units.

Answer the following question.

Although ΔS for the formation of two moles of water from H₂ and O₂ is –327J K^–1, it is spontaneous. Explain.
(Given ΔH for the reaction is –572 kJ).