Which one is most reactive towards S_N1 reaction?

1. $C_6{H}_{5}CH\left(C_6{H}_5\right)Br$

2. $C_6{H}_{5}CH\left(C{H}_3\right)Br$

3. $C_6{H}_{5}C\left(C{H}_3\right)\left(C_6{H}_5\right)Br$

4. $C_6{H}_{5}C{H}_{2}Br$

AB crystallizes in a body-centered cubic lattice with edge length 'a' equal to 387 pm. The distance between two oppositely charged ions in the lattice is:

1. 335 pm

2. 250 pm

3. 200 pm

4. 300 pm

The number of atoms in 0.1 mole of a triatomic gas is (N_A= 6.02 x 10²³ mol^-1):

1. $6.026\times {10}^{22}$

2. $1.806\times {10}^{23}$

3. $3.600\times {10}^{23}$

4. $1.800\times {10}^{22}$

Which of the following molecular hydrides acts as a Lewis acid?

1. $N{H}_3$

2. $H_{2}O$

3. $B_2{H}_6$

4. $C{H}_4$

The tendency of BF₃, BCl₃ and BBr₃ to behave as Lewis acid decreases in the sequence:

1. $BC{l}_3>B{F}_3>BB{r}_3$

2. $BB{r}_3>BC{l}_3>B{F}_3$

3. $BB{r}_3>B{F}_3>BC{l}_3$

4. $B{F}_3>BC{l}_3>BB{r}_3$

In vitro fertilization is a technique that involves the transfer of which one of the following into the Fallopian tube?

1. Embryo only, upto 8 cell stage

2. Either zygote or early embryo up to 8 cell stage

3. Embryo of 32 cell stage

4. Zygote only

Which one of the following structures between two adjacent cells is an effective transport pathway?

1. Plasmodesmata

2. Plastoquinones

3. Endoplasmic reticulum

4. Plasmalemma

Single-celled eukaryotes are included in:

1. Protista

2. Fungi

3. Archaea

4. Monera

The genetically-modified (GM) brinjal in India has been developed for:

1. insect-resistance

2. enhancing self-life

3. enhancing mineral content

4. drought-resistance

In unilocular ovary with a single ovule, the placentation is:

1. marginal

2. basal

3. free central

4. axile