Chemistry Test 216

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Chemistry Test 216

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Weekly Quiz Competition

Question 1
4 / -1

The radioactive isotope which is used in the treatment of cancer, can be made by (n, p) reaction. What is the target nucleus for this reaction?

A

B

C

D

Solution
Question 2
4 / -1

The bond lengths and bond angles in the molecules of methane, ammonia and water are given below:

This variation in bond angle is a result of

(i) the increasing repulsion between hydrogen atoms as the bond length decreases

(ii) the number of non-bonding electron pairs in the molecule

(iii) a non-bonding electron pair having a greater repulsive force than a bonding electron pair

A
(i), (ii) and (iii)

B
(i) and (ii)

C
(ii) and (iii)

D
(i)

Solution

In methane, ammonia and water, the central atom is sp³ hybridised and expected bond angle is 109.5°.

However, the bond angle changes due to the presence of lone pairs of electrons.

This is because: lone pair-lone pair repulsions > lone pair-bond pair repulsions > bond pair-bond pair repulsions.

Methane (no lone pair) has a regular tetrahedral geometry with bond angle of 109.5°.

Ammonia (one lone pair) has a pyramidal geometry with bond angle of 107°.

Water (two lone pairs) has an angular bent geometry with bond angle of 104.5°.
Question 3
4 / -1

For a first order reaction A P, the temperature (T) dependent rate constant (k) was found to follow the equation log

The pre-exponential factor A and the activation energy E_a respectively are

A
1.0 × 10⁶ s^-1 and 9.2 kJ mol^-1

B
6.0 s^-1 and 16.6 kJ mol^-1

C
1.0 × 10⁶ s^-1 and 16.6 kJ mol^-1

D
1.0 × 10⁶ s^-1 and 38.3 kJ mol^-1

Solution
Question 4
4 / -1

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

Wavelengths of X-ray lines of Mg and Cr are 0.987 nm and 0.229 nm, respectively. The values of the constants 'a' and 'b' for this series should respectively be

A
9.8 × 10⁷ and 0.758

B
4.9 × 10⁷ and 0.385

C
4.9 × 10⁷ and 0.785

D
9.8 × 10⁷ and 0.658

Solution
Question 5
4 / -1

Identify the incorrect statement.

A
Cl₂ reacts with excess of NH₃ to give N₂ and HCl.

B
Br₂ reacts with hot and strong NaOH solution to give NaBr, NaBrO₃ and H₂O.

C
Ozone reacts with SO₂ to give SO₃.

D
Silicon reacts with NaOH(aq) in the presence of air to give Na₂SiO₃ and H₂O.

Solution

Cl₂ reacts with excess of NH₃ to give N₂ and ammonium chloride. The chemical reactions involved in this process are as follows.

Hence, the reaction described in the option (1) is incorrect.
Question 6
4 / -1

The gas leaked from a storage tank of the Union Carbide plant in the Bhopal gas tragedy was

A
phosgene

B
methyl isocyanate

C
methylamine

D
ammonia

Solution

Methyl isocyanate (MIC) is extremely toxic.

The toxic effect of the compound was apparent in the 1984 Bhopal disaster, when around 42,000 kilograms (93,000 lb) of methyl isocyanate and other gases were released from the underground reservoirs of the Union Carbide India Limited (UCIL) factory, over a populated area on December 3, 1984, killing about 3500 people immediately and 15,000 more over the next several years.
Question 7
4 / -1

What would be the product formed when 1-bromo-3-chlorocyclobutane reacts with two equivalents of metallic sodium in ether?

A

B

C

D

Solution

In Wurtz reaction, an ether solution of an alkyl halide gives an alkane when heated with metallic sodium.

For different halogens it is in the order: iodide > bromide > chloride

Since bromides are more reactive than chlorides in Wurtz reaction, Wurtz reaction occurs on the side of Br atom.
Question 8
4 / -1

Consider the following sequence of reactions:

The end product Q is

A

B

C

D

Solution
Question 9
4 / -1

Identify product 'Z' in the following reaction scheme:

A
p-Bromoaniline

B
p-Bromoacetophenone

C
p-Bromoacetanilide

D
o-Bromoacetophenone

Solution
Question 10
4 / -1

Which of the following characteristics is/are not correct for enzymes?

a. Enzymes show maximum activity when pH is either very low or very high.

b. Enzymes are normally heterogeneous catalysts that are very specific in action.

c. Enzymes are specific biological catalysts that possess well-defined active sites.

d. Chemically, all enzymes are globular proteins.

A
Only a

B
b and c

C
Only c

D
a and d

Solution

Statement 'a' is wrong as different enzymes are active at different pH values, but most enzymes function in pH around 7.4.