Haryana Board (HBSE) Class 11 Chemistry SAT-2 Question Paper 2025 Answer Key
Instructions :
• All questions are compulsory.
• Questions (1-8) carry 1 mark each.
• Questions (9-10) carry 2 marks each.
• Question (11) carry 3 marks.
• Question (12) carry 5 marks.
1. Which of the following relation is correct?
(a) K3 = K1/K2
(b) K3 = K1 + K2
(c) K1 = K2K3
(d) K3 = K1K2
Answer – (d) K3 = K1K2
2. If Kp for a reaction :
A(g) + 2B(g) = 3C(g) + D(g)
is 0.05 atm at 1000 K. Its Kc in terms of R will be :
(a) 20000 R
(b) 0.02 R
(c) 5 × 10–5/R
(d) 5 ×105 R
Answer – (c) 5 × 10–5/R
3. Oxidation is :
(a) loss of electrons
(b) addition of hydrogen
(c) decrease in oxidation number
(d) all of these
Answer – (a) loss of electrons
4. Oxygen has an oxidation state +2 in :
(a) H2O2
(b) OF2
(c) H2O
(d) SO2
Answer – (b) OF2
5. Oxidation state of nitrogen in NO3– is :
(a) +1
(b) +2
(c) +3
(d) +5
Answer – (d) +5
6. Write the IUPAC name of neo pentane.
Answer – 2,2-dimethylpropane
7. The bond order of individual carbon-carbon bonds in benzene is lie between…………
Answer – one and two
8. Which is known as Baeyer’s reagent?
Answer – Alkaline KMnO4 solution
9. Write chemical equation for the combustion reaction of the following hydrocarbons :
(i) Butane (C4H10)
Answer – 2C4H10 + 13O2 → 8CO2 + 10H2O + Energy
(ii) Pentene (C5H10)
Answer – 2C5H10 + 15O2 → 10CO2 + 10H2O + Energy
(iii) Hexyne (C6H10)
Answer – 2C6H10 + 17O2 → 12CO2 + 10H2O + Energy
OR
What is the initial effect of the change on vapour pressure?
Answer – On heating, more liquid molecules gain enough kinetic energy to escape from the liquid surface into vapour phase, so vapour pressure rises. On cooling, fewer molecules escape, so vapour pressure falls.
10. What effect does branching of an alkane chain has on its boiling point?
Answer – The boiling point of alkanes increases with increase in carbon chain length, but decreases on branching. Branching makes the molecule more compact, reducing its surface area and hence intermolecular (van der Waals) forces, which lowers the boiling point. Example: Pentane has a higher boiling point than 2-methylbutane because pentane has a straight chain with a larger surface area, while 2-methylbutane is branched.
OR
How to rates of evaporation and condensation change initially?
Answer – When conditions like temperature are increased, the rate of evaporation increases immediately, while the rate of condensation remains unchanged initially. After some time, as more vapour is formed, the rate of condensation also increases and finally both rates become equal again at equilibrium.
11. What is the minimum volume of water required to dissolve one gram of calcium sulphate at 298 K? (Ksp for CaSO4 = 9.1 ×10–6)
Answer – Here, Ksp = s2 = 9.1 × 10–6
s = √9.1×10–6 = 3.02 × 10–3 M
The molar (molecular) mass of CaSO4 (calcium sulphate) = 136 g mol–1
Moles in 1g CaSo4 = 1/136 = 7.35 × 10–3 mol
Volume = moles / s = 7.35×10–3 / 3.02×10–3 = 2.43 L
12. (a) Write Bond line formula for :
isopropyl alcohol, 2,3-dimethylbutan-1-ol & heptan-4-one
Answer – isopropyl alcohol = CH3 – CH(OH) – CH3
2,3-dimethylbutan-1-ol = CH3 – CH(CH3) – CH(CH3) – CH2OH
heptan-4-one = CH3 – CH2 – CH2 – CO – CH2 – CH2 – CH3
(b) Explain why alkyl groups act as electron donors when attached to the π system?
Answer – Alkyl groups act as electron donors when attached to a π system because they exhibit a +I (electron-releasing inductive) effect and hyperconjugation. Through the +I effect, alkyl groups push electron density toward the carbon framework of the π system. At the same time, the σ-electrons of the C–H bonds in the alkyl group can overlap with the adjacent π orbitals, allowing partial delocalisation of electrons, a phenomenon known as hyperconjugation. As a result, electron density of the π system increases, so alkyl groups behave as electron-donating groups and stabilize the π system.