Which is $NOT$ an example of a macromolecular colloid?

The radiation emitted by a star $A$ is $10000$ times that of the sun. If the surface temperatures of the sun and the star $A$ are $6000 \ K$ and $2000 \ K$ respectively,the ratio of the radii of the star $A$ and the sun is : (in $: 1$)

Which of the following ecosystem types has the highest annual net primary productivity?

$A$ candle of diameter $d$ is floating on a liquid in a cylindrical container of diameter $D$ $(D >> d)$ as shown in the figure. If it is burning at the rate of $2 \ cm/hour$,then the top of the candle will

In which of the following,ortho/para substitution by an electrophile is very facile?

Calculate the electric field at the origin due to an infinite number of charges as shown in the figure.