In Bryophytes,which stage produces haploid,autotrophic gametes?

The refractive index of a material of a plano-concave lens is $5/3$,and the radius of curvature is $0.3 ~m$. The focal length of the lens in air is (in $~m$)

If the extremities of a diagonal of a square are $(1, -2, 3)$ and $(2, -3, 5)$,then the length of its side is

$A$ class has $15$ boys and $5$ girls. Suppose $3$ students are selected at random from the class. The probability that there are $2$ boys and $1$ girl is

The equations of the tangents to the circle $x^2 + y^2 = 13$ at the points whose abscissa is $2$,are

Let a random variable $X$ have a binomial distribution with mean $8$ and variance $4$. If $P(X \le 2) = \frac{k}{2^{16}}$,then $k$ is equal to