For a first order reaction A ⟶ P,the temperature (T) dependent rate constant (k) was found to follow the equation log k= –(2000)\(\frac{1}{T}\) + 6.0. The pre-exponential factor A and the activation energy E_a, respectively, are

1.0 × 10⁶ s^-1 and 9.2kJ mol^-1
6.0 s^-1 and 16.6 kJ mol^-1
1.0 × 10⁶ s^-1 and 16.6 kJ mol^-1
1.0 × 10⁶ s^-1 and 38.3 kJ mol^-1

Solution

In crystals which one of the following ionic compounds would you expect maximum distance between centres of cations and anions?

Solution

As Cs⁺ ion has larger size than Li⁺ and I^- has larger size than F^-, therefore maximum distance between centres of cations and anions is in CsI.

Which one of the following is flourspar?

CaF₂
CaO
H₂F₂
CaCO₃

benzonitrile
benzaldehyde
benzoic acid
benzylamine

Solution

An unknown compound ‘D’ first oxidised to aldehyde and then acetic acid by a dilute solution of K₂Cr₂O₇ and H₂SO₄.The compound ‘D’ is:

CH₃OH
C₂H₅OH
CH₅CH₂COOH
CH₃CH₂CHO

Solution

0.4 moles of HCl and 0.2 moles of CaCl₂ were dissolved in water to have 500 mL of solution, the molarity of Cl^–ion is:

0.8 M
1.6 M
1.2 M
10.0 M

Solution

Which one of the following will show paramagnetism corresponding to 2 unpaired electrons?(Atomic numbers : Ni = 28, Fe = 26)

[FeF₆]^3–
[NiCl₄]_2–
[Fe (CN)₆]^3–
[Ni (CN)₄]^2-

Solution

As in [NiCl₄]^2- Chloride ion being a weak ligand is notable to pair the electrons in d orbital.

Which of the following has the highest pπ– pπ bonding tendency ?

Solution

Nitrogen due to small size is able to show pπ-pπ lateral overlap forming N ≡ N, rest elements due to bigger size are not able to show pπ-pπ lateral overlap.

The ratio ^a⁄_b (a and b being the van der Waal’s constants of real gases) has the dimensions of

atm mol^-1
L mol^-1
atm L mol^-1
atm L mol^-2

Solution

Three sparingly soluble salts A₂B, AB and AB₃ have the same values of solubility products (K_sp). In a saturated solution the correct order of their solubilities is

AB₂ > AB >> A₂B
AB₃ > A₂B > AB
AB > AB₃ > A₂B
AB > A₂B > AB₃

Solution

The rise in the boiling point of a solution containing 1.8 g of glucose in 100 g of solvent is 0.1°C. The molal elevation constant of the liquid is

0.01 K/m
0.1 K/m
1 K/m
10 K/m

Solution

K_b = \(\frac{0.1 \times 180 \times 100}{1.8 \times 1000}\) = 1 K/m

Solution

Nitrogen can not be pentavalent as it has no d-orbitals

Which one of the following elements shows maximum number of different oxidation states in its compounds?

Solution

We know that lanthanides La, Gd shows +3, oxidation state, while Eu shows oxidation state of +2 and + 3. Am shows +3, +4, +5 and +6 oxidation states. Therefore Americium (Am) has maximum number of oxidation states

In coagulating the colloidal solution of As₂S₃ which has the minimum coagulating value ?

NaCl
KCl
BaCl₂
AlCl₃

Solution

As₂S₃ is negative sol.For coagulating negative sol Al³⁺ is most effective. It is because higher the magnitude of the charge, the lower is coagulating value.

Solution

The following compound will undergo electrophilic substitution more readily than benzene :

Nitrobenzene
Benzoic acid
Benzaldehyde
Phenol

Solution

Due to + M effect of the – OH group in phenol, electron density in the ortho and para positions of the phenol nucleus increases hence phenol will undergo electrophilic substitution easily than benzene. The other three compounds have electron withdrawing groups,hence they will undergo electrophilic substitution with a difficulty than benzene.

Which one of the following ions is the most stable in aqueous solution?

(At.No. Ti = 22, V = 23, Cr = 24, Mn = 25)