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Mixed Chemistry Test

Description: This test is based on certain topics fron chemistry which are of great help foe engineering aspirants.
Number of Questions: 25
Created by:
Tags: Acids Bases & Salts metallurgy ligands etc Factors Affecting Rate of a Reaction Chemical Kinetics Zero and First Order Reaction Integrated Rate Equations Collision Theory of Chemical Reactions Zero Order Reactions Rate of a Reaction Rate of a Chemical Reaction
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Directions: The following question has four choices out of which ONLY ONE is correct.

Find the wrong statement regarding the factors affecting the chemical reactions.

  1. The rate of photochemical reaction is independent of radiations.

  2. A catalyst increases the rate of a chemical reaction at a particular temperature only.

  3. The rate of chemical reaction is directly proportional to the concentration of the reactants.

  4. The rate of chemical reaction depends on number of collisions.


Correct Option: A
Explanation:

The rate of photochemical reaction increases by absorption of photons of certain radiations.

Which of the following statements is incorrect regarding the postulates of collision theory of chemical reactions?

  1. The colliding molecules should possess threshold energy to yield products.

  2. Activation energy = [Threshold energy - energy of the molecules at normal state]

  3. The molecules acquiring the threshold energy are called activated molecules.

  4. All collisions between the reacting molecules can form the products.


Correct Option: D
Explanation:

Collisions taking place between activated molecules are called activated collisions. Only the activated collisions can lead to the formation of the products in the chemical reaction.

Directions: The following question has four choices out of which ONLY ONE is correct.

Decomposition of NH3 in presence of molybdenum or tungsten is an example of

  1. first order reaction

  2. second order reaction

  3. zero-order reaction

  4. third order reaction


Correct Option: C
Explanation:

Decomposition of NH3 in presence of molybdenum or tungsten is a zero order reaction.

The differential rate law expression for second order reaction is represented as

    • d[A]/dt = K
  1. -d[A]/dt = K [A]

  2. -d[A]/dt = K [A]2

  3. -d[A]/dt = K 2[A]


Correct Option: C
Explanation:

This is differential rate law expression for second order reaction.

Directions: The following question has four choices out of which ONLY ONE is correct.

Which of the following methods is used to determine the order of a reaction with respect to one reactant at a time?

  1. Ostwald Isolation Method

  2. Hit and trial method

  3. Graphical method

  4. Half life method


Correct Option: A
Explanation:

This method is used to determine the order of a reaction with respect to one reactant at a time. The total order of the reaction can be calculated by adding all the orders of the reaction for individual reactant.

A mixture of 4 g of H2 and 128 g of HI is prompted in a 2 litre flask. What will be its respective active mass?

  1. 0.5 mol L-1

  2. 0.05 mol L-1

  3. 0.005 mol L-1

  4. 0.0005 mol L-1


Correct Option: A
Explanation:

Mass of hydrogen = 4 g, Mol. mass of hydrogen = 2; Volume of the flask = 2 litres. Active mass of hydrogen = 4/2 X 2 = 1 mol L-1Mass of HI = 128 g, Mol. mass of HI = 128 g, Volume of the flask = 2 litre. Active mass of hydrogen iodide = 128/(128 X 2) = 0.5  mol L-1                                                      

Directions: The following question has four choices out of which ONLY ONE is correct.

Which among the following is not a zero order reaction?

  1. Photochemical reaction between hydrogen and chlorine

  2. Decomposition of N2O on hot platinum surface

  3. Iodinations of acetone in presence of H+ ions

  4. Thermal decomposition of chlorine monoxide


Correct Option: D
Explanation:

Thermal decomposition of dichlorine monoxide is a second order reaction. 2Cl2O → 2Cl2 + O2

Directions: The following question has four choices out of which ONLY ONE is correct.

Find out the wrong statement regarding the characteristics of photochemical reactions.

  1. Each molecule participating in a photo process absorbs multiple photons of radiant energy.

  2. The rate of photochemical reaction is dependent on the intensity of absorbed radiation.

  3. These reactions do not take place in dark.

  4. These reactions are independent of temperature.


Correct Option: A
Explanation:

Each molecule participating in a photochemical process absorbs only one photon of radiant energy. Thus, it can increase its energy level by hv only.

Which among the following is not a correct formulation of Arrhenius equation?

  1. k = Ae–Ea/RT

  2. log k = log A – Ea/2.303 RT

  3. log k2/k1 = Ea/2.303R [1/T1 – 1/T2]

  4. k = AeE/RT


Correct Option: D
Explanation:

The equation is called Arrhenius equation.

The Kp for the formation of ammonia at 250 0C is 1.42x10-5 atm. Find the Kc for this reaction.

  1. 0.057

  2. 0.0057

  3. 0.57

  4. 0.66


Correct Option: A
Explanation:

The equation for the above reaction is

N2  + 3H2 -----------------> 2NH3   (Δ n = 2 - (1+3)  = -2)

Kp = 1.42x10-5

T = 273 + 500

     = 773 K

R = 0.0821 L.atm/mol.K

By substituting the values in the following expression, we have

Kc = Kp/ (RT) Δ n

1.42x10-5/ (0.0821 x 773)-2 = 0.057

In a chemical reaction, 13.4 litres of HI were formed by the reaction between 8.1 litres of H2 and 9.1 litres of I2 at 3500C. Calculate the Kp for this reaction.

  1. 51.84

  2. 50.01

  3. 60.61

  4. 60.89


Correct Option: A
Explanation:

H2 + I2 ----------------->2HI

Let us assume that at equilibrium, x litres of hydrogen reacts with x litres of iodine to form 2x litres of hydrogen iodide.

It is given that 2x = 13.4

Therefore, x = 6.7

Now let us write the given reaction.

 

Initial vol                                                 8.1         9.1          0

Initial moles                                            a              b            0                                                                H2       +  I2     ----------------->2HI

At equilibrium                                        (a-x)        (b-x)         2x                                                       (8.1-6.7)      (9.1-6.7)   13.4

The equilibrium constant of the reaction is given as                [HI]2       Kc = ------------                  (a-x) (b-x)                 (13.4)2       =   ------------                  (1.4) (2.4) = 51.84  

Which among the following can be excluded from the consequences of Schottky defects?

  1. The volume of the crystal increases.

  2. The density of the solid decreases.

  3. The crystal conduct electricity to a small extent.

  4. The crystal posses lower lattice energy than stability.


Correct Option: A
Explanation:

It is not consequence of Schottky defect. The volume of the crystal remains unaffected.

A chemical reaction at equilibrium is exothermic in the forward direction and endothermic in backward direction. What is the effect of increase of temperature on it?

  1. The equilibrium will shift in the backward direction so as to consume the heat evolved.

  2. The equilibrium shifts in the forward direction so as to liberate more heat.

  3. Equilibrium is not affected by change of temperature.

  4. It cannot be predicted.


Correct Option: A
Explanation:

According to Le Chateliers principle, the increase of temperature should shift the reaction in the direction of absorbing the heat, i.e. the backward direction. So, the equilibrium will shift in the backward direction to consume the heat evolved.

In a certain chemical reaction, the number of moles of products are lesser than the number of reactants. What will happen if the pressure on the system is increased?

  1. Equilibrium will shift in the backward direction forming more reactants so as to minimise the extent of formation of products.

  2. Equilibrium will shift toward in the direction of the formation of products so as to minimise the applied pressure.

  3. Equilibrium remains unaffected by increasing the pressure.

  4. It cannot be predicted.


Correct Option: B
Explanation:

As per the Le Chatelier's principle, the increase of external pressure shifts the equilibrium in a direction which lowers the pressure, i.e. the equilibrium shifts in a direction that forms lesser number of moles of the gas.

All the molecules of a gas are in constant motion. Which of the following statements regarding the nature of this motion is incorrect?

  1. As the gas molecules are elastic in nature there is no loss of energy when the molecules collide. But some energy is transferred during the time of collision.

  2. All the molecules of a gas are in constant motion.

  3. There is a large distance between the gaseous molecules.

  4. The kinetic energy of all the gaseous molecules is independent of the absolute temperature.


Correct Option: D
Explanation:

The average kinetic energy of all the gaseous molecules is directly proportional to the absolute temperature. The increase in temperature increases the kinetic energy of the molecules and hence they move at greater speed.

Human body is an example of

  1. isolated system

  2. closed system

  3. adiabatic system

  4. open system


Correct Option: D
Explanation:

This system involves the exchange of both matter and energy with the surroundings. Since, human body exchanges both matter and energy with the surroundings, it is an open system.

Which of the following entropies is lost upon carrying together two residues of a polymer within an assigned distance?

  1. The Sackur-Tetrode entropy

  2. Free entropy

  3. Conformational entropy

  4. Loop entropy


Correct Option: D
Explanation:

It is the entropy lost upon carrying together two residues of a polymer within a assigned distance.

Which of the following entropies is a chronic analytical mechanical entropy of a thermodynamic system?

  1. Gibbs entropy

  2. Boltzmann entropy

  3. Tsallis entropy

  4. Residual entropy


Correct Option: A
Explanation:

It is the chronic analytical mechanical entropy of a thermodynamic system.

Which among the following terms lies at the intersection of entropy and life?

  1. Negentropy

  2. Ectropy

  3. Extropy

  4. Ecological entropy


Correct Option: A
Explanation:

It is a scribble colloquial phrase for negative entropy lying at the intersection of entropy and life.

The basic ideas of the second law of thermodynamics were first put forwarded by

  1. Rudolf Clausius

  2. John Rayleigh

  3. Walther Nernst

  4. August Karl


Correct Option: A
Explanation:

Rudolf Clausius was a German physicist and is a prominent scientist thermodynamics. He is famed for first stating the basic ideas of the second law of thermodynamics.

Which of the following boilers have hemispherical ends to withstand higher pressures?

  1. Donkey boiler

  2. Egg-ended boiler

  3. Fairlie boiler

  4. Fire-tube boiler


Correct Option: B
Explanation:

It is an early form of tubular wagon boiler. It possses hemispherical ends to withstand higher pressures.

If three elements M, N and O are crystallized in cubic solid lattice with M atoms at corners, N atoms at cube centre & O atoms at the edges, then the formula of the compound is

  1. MNO

  2. MN3O

  3. MNO3

  4. M3NO


Correct Option: C
Explanation:

Atom M is shared by 8 corners; 1 atom of O is shared by 4 unit cells. Atom N is present at centre of the unit cell. Hence, the effective number of atoms of M per unit cell = 8 X 1/8 = 1. The effective number of atoms of O per unit cell = 12/4 = 3.The effective number of atoms of N per unit cell = 1. Hence, the formula of the compound is MNO3.

Which engine is potentially used for pumping water from a mine?

  1. Beam engine

  2. Blowing engine

  3. Cornish engine

  4. Atmospheric engine


Correct Option: C
Explanation:

It is a type of steam engine being potentially used for pumping water from a mine.

Which of the following engines is capable of whirling dynamos to produce electricity?

  1. Barring engine

  2. Table engine

  3. Uniflow engine

  4. Corliss engine


Correct Option: D
Explanation:

This engine was generally utilised as stationary engines to give mechanical power to line shafting in factories and mills and to whirl dynamos to produce electricity.

In which of the following engines 'heavy oil' was first used as a fuel?

  1. Gas engine

  2. Hot bulb engine

  3. Hornsby-Akroyd oil engine

  4. Hit-and-miss engine


Correct Option: C
Explanation:

It was the first acknowledged draft of internal combustion engine using 'heavy oil' as a fuel. It was the first to use a separate vaporizing combustion chamber.

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