Who divided the $Angiosperms$ into two classes?

The right atrium of the human heart receives blood from which of the following?

The pressure of an ideal gas varies with volume as $P = \alpha V$,where $\alpha$ is a constant. One mole of the gas is allowed to undergo expansion such that its volume becomes $m$ times its initial volume. The work done by the gas in the process is

Assertion $(A)$: Equal moles of different substances contain the same number of constituent particles.
Reason $(R)$: Equal weights of different substances contain the same number of constituent particles.
The correct answer is

Breeding of crops with high levels of minerals,vitamins,and proteins is called:

Animals devoid of respiratory,excretory,and circulatory organs are: