The general term of the G.P. $\dfrac{1}{4}, -\dfrac{1}{2}, 1, -2, 4, \dots$ is :

1. (-1)^{(n - 1)} × 2^{(n - 3)}

2. (-1)^{(n - 1)} × 2^{(n - 2)}

3. (-1)^{(n - 1)} × (-2)^{(n - 1)}

4. (-1)^{(n - 1)} × (-2)^{(n - 3)}

The 12th term of the G.P. 2, 4, 8, 16, ……. is :

1. 1024

2. 2048

3. 4096

4. 8192

If a₁, a₂, a₃, ……., a_n is a G.P. having common ratio r and k is a natural number such that 3 < k < n, then r is equal to :

1. $\dfrac{a$k}{a{1}}

2. $\dfrac{a$1}{a2}

3. $\dfrac{a$k}{a{n-3}}

4. $\dfrac{a${k-1}}{a{k-2}}

The common ratio of the G.P. $-\dfrac{3}{4}, \dfrac{1}{2}, -\dfrac{1}{3}, \dfrac{2}{9}, \dots$ is :

1. $-\dfrac{4}{3}$

2. $-\dfrac{2}{3}$

3. $\dfrac{2}{3}$

4. $-\dfrac{3}{8}$