The shadow of a tower standing on a level ground is found to be $60 \, m$ longer when the sun's altitude is $30^\circ$ than when it is $45^\circ$. The height of the tower is

Three blocks $A, B$ and $C$ of masses $4\, kg$,$2\, kg$ and $1\, kg$ respectively,are in contact on a frictionless surface,as shown. If a force of $14\, N$ is applied on the $4\, kg$ block,then the contact force between $A$ and $B$ is .......... $N$.

The number of points $P(x, y)$ with natural numbers as coordinates that lie inside the quadrilateral formed by the lines $2x + y = 2$,$x = 0$,$y = 0$,and $x + y = 5$ is

An ideal gas is subjected to a cyclic process involving four thermodynamic states. The amounts of heat $(Q)$ and work $(W)$ involved in each of these states are:
$\begin{aligned} & Q_1=6000 \text{ J}, \quad Q_2=-5500 \text{ J}, \quad Q_3=-3000 \text{ J}, \quad Q_4=3500 \text{ J} \\ & W_1=2500 \text{ J}, \quad W_2=-1000 \text{ J}, \quad W_3=-1200 \text{ J}, \quad W_4=x \text{ J} \end{aligned}$
The ratio of the net work done by the gas to the total heat absorbed by the gas is $\eta$. The values of $x$ and $\eta$ respectively are:

The ether that undergoes electrophilic substitution reactions is

Differentiate between Asexual reproduction and Sexual reproduction.