Two pink coloured flowers on crossing resulted in $1$ red,$2$ pink and $1$ white flower progeny. The nature of the cross will be

$A$ zygote which has an $X-$ chromosome inherited from the father will develop into a

How many pairs of chromosomes are present in human beings (in $pairs$)?

$A$ palaeontologist (a scientist who studies fossils) finds the fossil of an organism in a deeper layer of the Earth. What method will they use to estimate its age?

In a pea plant,find the contrasting trait for the following:
$(a)$ The position of the flower is terminal.
$(b)$ The flower is white in colour.
$(c)$ The shape of the pod is constricted.

An angiosperm plant having red coloured flowers when crossed with another having the same colour produced $40$ progenies,out of which $30$ plants were with red coloured flowers and $10$ plants were with white coloured flowers. Find out:
$(a)$ What is the possible genotype of parent plants?
$(b)$ Which trait is dominant and which is recessive?
$(c)$ What is this cross called and what is its phenotypic ratio?