IIT-JEE Practise paper-14 [Test]

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Muggu

IIT-JEE Practise paper-14

A test by Muggu.

Test Questions

Question

The ratio of time periods in first and second orbits of hydrogen atom is;

Answers

Correct	Answer Text
	1:2
	1:8
	2:1
	1:4

Question

In a hydrogen atom, the largest amount of energy will be required in;

Answers

Correct	Answer Text
	$n_2 \rightarrow n_3$ transition
	$n \infty \rightarrow n_1$ transition
	$n_1 \rightarrow n_2$ transition
	$n_3 \rightarrow n_5$ transition

Question

The temperature coefficient of a reaction is 2, by what factor the rate of reaction increases when temperature is increased from 30^0C to 80^0C .

Answers

Correct	Answer Text
	128
	32
	16
	64

Question

For a given reaction of first order , it takes 20 min, for the concentration to drop from 1 $ML^{-1}$ to 0.6 $ML^{-1}$ .The time required for the concentration to drop from 0.6 $ML^{-1}$ to 0.36 $ML^{-1}$ will be

Answers

Correct	Answer Text
	$\infty$
	= 20 min
	< 20 min
	>20 min

Question

Answer the following 6 questions on the basis of the given below paragraph.

Physical and chemical equilibria respond stress, e.g. change in pressure, temperature and concentration of reactants and products. According to Le Chatelier’s principal a system at equilibrium, when subjected to a disturbance (stress), responds in a way that tends to minimize the effect of the disturbance.

Effect of pressure :- The principle implies that if a system at equilibrium is compressed, the reaction will adjust so as to minimize the increase in pressure. Thus, if volume of gas phase reaction system is reduced, the equilibrium shifts in the direction in which number of moles decreases. Although equilibrium constant is independent of pressure (at a fixed temperature), the various concentrations are changed on reducing the volume of the system, i.e., increasing the pressure.

However, if increase in pressure is effected by introducing an inert gas to the reaction vessel of constant volume, partial pressures or concentrations of various species remain unchanged as they continue to occupy the same volume. But at constant pressure condition, introduction of inert gas into the reaction system will lead to increase in volume and in consequence to the change in concentrations of various species. Under this condition, the equilibrium shifts in the direction in which number of moles of gaseous species increases.

Effect of temperature :- Le Chatelier principal predicts a system at equilibrium will tend to shift in the endothermic direction when temperature is raised, for then energy is absorbed as heat and the rise in temperature is opposed. Conversely, an equilibrium will shift in the exothermic direction if the temperature is lowered, for then heat energy is released and the reduction in temperature is opposed Van’t Hoff equation shows the dependence of equilibrium constant K on temperature as:

$\frac{d}{dt}log K=\frac{\Delta H^0}{RT^2}$ or log $K=constant- \frac{\Delta H^0}{R}. \frac{1}{T}$

Effect of addition of reactants or products ; On addition of one or more reactants, the equilibrium will shift to the products side so that the added reactants are consumed and increase in their concentrations is opposed. Addition of one or more products causes the equilibrium to shift in backward direction.

Consider the equilibrium,
$2CO+O_2 \leftrightharpoons 2CO_2+heat$
IF O_2 is added and volume of the reaction vessel is reduced, the equilibrium will;

Answers

Correct	Answer Text
	shift in forward direction
	remain unchanged
	be unpredictable
	shift in reverse direction

Question

A system at equilibrium is described by the equation

$Heat + SO_2Cl_2 \leftrightharpoons SO_2+Cl_2$ If some Cl_2 is added to the equilibrium mixture at constant volume, the temperature of the system will;

Answers

Correct	Answer Text
	fluctuate
	not change
	decrease
	increase

Question

The volume of the systems decribing the equilibria;

$(I) Heat + MgCO_{3s} \leftrightharpoons MgO_{(s)} + CO_{2(s)}$

$(II) 2C_{s} +O_{2(g)} \leftrightharpoons 2CO_{(s)} + heat$

is decreased. The equilibria will shift.

Answers

Correct	Answer Text
	to the right in (I) and to the left in (II)
	to the right in both (I) and II
	to the left in both (I) and II
	to the left in (I) and to the right in (II)

Question

Manufacture of lime from lime stone as;

$CaCO_{3(s)} + Heat \rightarrow CaCO_{(s)} + CaCO_{2(g)}$ is most favoured by;

Answers

Correct	Answer Text
	adding more lime stone to the reaction chamber
	heating lime stone is an open chamber
	adding more lime stone to the reaction chamber
	heating lime stone in a closed chamber

Question

Consider the reaction,

$A + B \leftrightharpoons C + D + heat$
What will happen when temperature is raised?

Answers

Correct	Answer Text
	the rate constant of forward reaction would decrease and that of reverse reaction would increase.
	The rate constants of both forward and reverse reactions would increase, former increasing less rapidly
	The rate constant of forward reaction would increase and that of reverse reaction would decrease.
	The equilibrium constant of the reaction increases.

Question

The plot of log K against 1/ T is a straight line with positive slope (K being the equilibrium constant of a reaction), which of the following is then correct?

Answers

Correct	Answer Text
	The reaction goes to farther extent on raising the temperature
	The reaction causes heating effect
	The reaction causes cooling effect
	None of these