Questions Paper JEE Mains

EEnvatX Team16 Oct 20262 min read

Q1. The binding energy per nucleon for the parent nucleus is E 1 and that for the daughter nuclei is E 2 . Then

E 2 = 2E 1
E 1 > E 2
E 2 > E 1
E 1 = 2E 2

Answer: C

Q2. A diatomic ideal gas is used in a car engine as the working substance. If during the adiabatic expansion part of the cycle, volume of the gas increases from V to 32 V, the efficiency of the engine is

0.5
0.75
0.99
0.25

Answer: B

Q3. If a source ol power 4 kW produces 1020 photons/second, the radiation belong to a part of the spectrum called

X-rays
ultraviolet rays
microwaves
y-rays

Answer: A

Q4. The respective number of significant figures for the numbers 23.023, 0.0003 & 2.1 × 10 –3 are

5, 1, 2 (b) 5, 1, 5
5, 5, 2 (d) 4, 4, 2

Answer: A

Q5. As the beam enters the medium, it will

diverge
converge
diverge near the axis and converge near the periphery
travel as a cylindrical beam

Answer: B

Q6. The standard enthalpy of formation of NH 3 is –46.0 kJ mol –1 If the enthalpy of formation of H 2 from its atoms is –436 kJ mol –1 and that of N 2 is –712 kJ mol –1 , the average bond enthalpy of N—H bond in NH 3 is

–964 kJ mol –1
+352 kJ mol –1
+1056 kJ mol –1
–1102 kJ mol –1

Answer: B

The time for half-life period of a certain reaction, A → products is 1 h. When the initial concentration of the reactant 'A', is

2.0 mol L –1 , how much time does it take for its concentration to come from 0.50 to 0.25 mol L –1 , if it is a zero order reaction?

(a) 4 h

(b) 0.5 h

(d) 1 h

Ans. c

A solution containing 2.675 g of CoCl 3 .6NH 3 (molar mass = 267.5 g mol –1 ) is passed through a cation exchanger. The chloride ions obtained in solution were treated with excess of AgNO 3 to give 4.78 g of AgCl (molar mass = 143.5 g mol –1 ). The formula of the complex is

(At mass of Ag = 108 u)