When a small amount of KMnO₄is added to concentrated H₂SO₄, a green oily compound is obtained which is highly explosive in nature. Compound may be :

MnSO₄
Mn₂O₇
MnO₂
Mn₂O₃

Solution

KMnO₂ reacts with H₂SO₄ to form Mn₂O₇ which is highly explosive substance.

2KMnO₄+ H₂SO₄ → K₂SO₄+ Mn
₂O₇ + H₂O

The correct name for NO₂ using stock notation is :

Nitrogen dioxide
Nitrogen (iv) oxide
Nitrogen peroxide
All of these

Solution

The method of representing oxidation number by a Roman numeral within the parenthesis represents Stock notation.

Which one of the following is not an allylic halide?

4-Bromopent-2-ene
3-Bromo-2-methylbut-1-ene
1-Bromobut-2-ene
4-Bromobut-1-ene

Solution

DIRECTIONS: These are Assertion-Reason type questions. Question contains two statements:Statement-1 (Assertion) and Statement-2 (Reason). Answer these questions from the following four options.

Statement-1:In any ionic solid (MX) with Schottky defects,the number of positive and negative ions are same.
Statement-2 :Equal number of cation and anion vacancies are present

Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation of Statement-1
Statement-1 is True, Statement-2 is True; Statement-2 is NOT a correct explanation of Statement-1
Statement-1 is True, Statement-2 is False
Statement-1 is False, Statement-2 is True

Solution

Schottky defect is due to missing of equal number of cations and anions.

25.3 g of sodium carbonate, Na₂CO₃ is dissolved in enough water to make 250 mL of solution. If sodium carbonate dissociates completely, molar concentration of sodium ions,Na⁺ and carbonate ions, \(CO_{3}^{2-}\) are respectively (Molar mass of Na₂CO₃ = 106 g mol^–1)

0.955 M and 1.910 M
1.910 M and 0.955 M
1.90M and 1.910 M
0.477 M and 0.477 M

Solution

Which of the following elements is present as the impurity to the maximum extent in the pig iron ?

Manganese
Carbon
Silicon
Phosphorus

Solution

Pig iron or cast iron contains 3 –5% carbon and varying amounts of Mn,Si, P and S which makes the iron hard and brittle.

Which of the following pairs will form the most stable ionic bond?

Na and Cl
Mg and F
Li and F
Na and F

Solution

The stability of the ionic bond depends upon the lattice energy which is expected to be more between Mg and F due to +2 charge on Mg atom.

If the shortest wavelength of the spectral line of H-atom in the Lyman series is X,then the longest wavelength of the line in Balmer series of Li²⁺ is

9x
^x⁄₉
^5x⁄₄
^4x⁄₅

Solution

In which one of the following molecules the central atom said to adopt sp² hybridization?

BeF₂
BF₃
C₂H₂
NH₃

Solution

BF₃ involves sp²-hybridization.

Which of the following compounds is a good conductor of electricity in solution state ?

Covalent
Molecular
Metallic
Ionic

Solution

Ionic compounds are dissociated in solution state and form ions. Ions are good carrier of charge which make solution conducting.

The stability of + 1 oxidation state increases in the sequence:

Tl < In
In < Tl < Ga < Al
Ga < In < Al < Tl
Al

Solution

The stability of +1 oxidation state increases from aluminium to thallium i.e.Al < Ga < In < Tl.

A metal salt solution forms a yellow precipitate with potassium chromate in acetic acid, a white precipitate with dil H₂SO₄, but gives no precipitate with NaCl. The metal salt solution will consist of

PbCO₃
BaCO₃
MgCO₃
CaCO₃

Solution

BaCO₃ forms a yellow ppt of barium chromate. BaCO₃ forms a white precipitate of BaSO₄. BaCl₂ is soluble in water.

Which of the following is the best description for the behaviour of bromine in the reaction given below ?

H²O + Br₂ → HOBr + HBr

Proton acceptor only
Both oxidized and reduced
Oxidized only
Reduced only

Solution

\(H_{2}O+\overset{0}{Br_{2}}\rightarrow \overset{+1}{HOBr}+ \overset{-1}{HBr}\)

Thus here oxidation number of Br increases from 0 to+1 and also decreases from 0 to –1. Thus it is oxidised as well as reduced.

Which one of the following pairs of species have the same bond order?

CN^- and NO⁺
CN^- and CN⁺
\(O_{2}^{-}\) and CN^-
NO⁺ and CN⁺

Solution

Magnesium form Mg²⁺ and Mg⁺ because :

ionic radius of Mg(II) is smaller than of Mg(I).
hydration energy of divalent magnesium ion is higher.
magnesium (II) carbonate is insoluble in water.
generally higher oxidation states are preferred by metals.

Solution

Statement (b) is correct.

Which of the following aqueous solution has minimum freezing point ?

0.01 m NaCl
0.005 m C₂H₅OH
0.005 m MgI₂
0.005 m MgSO₄

Solution

Which one of the following orders of acid strength is correct?

RCOOH > HC \(\equiv\) CH> HOH > ROH
RCOOH > ROH > HOH > HC \(\equiv\) CH
RCOOH > HOH > ROH > HC \(\equiv\) CH
RCOOH > HOH > HC \(\equiv\) CH > ROH

Solution

The higher is the tendency to donate proton, stronger is the acid. Thus the correct order is R – COOH > HOH > R – OH >CH \(\equiv\) CH depending upon the rate of donation of proton.

Which of the following carbonyls will have the strongest C – O bond ?

[Mn (CO)₆]⁺
[Cr (CO)₆]
[V (CO)₆]^-
[Fe (CO)₅]

Solution

As positive charge on the central metal atom increases,the less readily the metal can donate electron density into the π* orbitals of CO ligand (donation of electron density into π* orbitals of CO result in weakening of C – O bond). Hence, the C – O bond would be strongest in [Mn(CO)₆]⁺.

The reason for almost doubling the rate of reaction on increasing the temperature of the reaction system by 10°C is

The value of threshold energy increases
Collision frequency increases
The fraction of the molecule having energy equal to threshold energy or more increases
Activation energy decreases

Solution

When the temperature is increased, energy in form of heat is supplied which increases the kinetic energy of the reacting molecules. this will increase the number of collisions and ultimately the rate of reaction will be enhanced.

Schottky defect generally appears in :

NaCl
KCl
CsCl
all of these

Solution

Schottky defect occurs in ionic crystals of type A+B,when equal number of cations and anions are missing from their lattice sites so that the electrical neutrality is maintained. This defect generally appears in highly ionic compounds which have high coordination number.NaCl, KCl and CsCl all have high coordination numbers i.e., 6, 6 and 8 respectively. So, Schottky defect appear in all of the given compounds.

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