Identify from the following plant parts,the major contributors to human food?

Below are two statements. One is labeled as Assertion $(A)$ and the other as Reason $(R).$
Assertion $(A):$ Gypsum is used to make boards for fireproof walls.
Reason $(R):$ Gypsum is unstable at high temperatures.
In the context of the above statements,choose the correct answer from the options given below:

$A$ satellite is launched into a circular orbit of radius $R$ around the Earth,while a second satellite is launched into an orbit of radius $1.02 R$. The percentage difference in the time periods of the two satellites is ......... $\%$

The de-Broglie wavelength of a particle accelerated with $150 \ V$ potential is $10^{-10} \ m$. If it is accelerated by $600 \ V$ potential difference,its wavelength will be ........... $\mathring{A}$.

The perimeter of a $\triangle ABC$ is $6$ times the arithmetic mean of the sine of its angles. If its side $BC$ is of unit length,then $\angle A=$

Consider the two following statements $A$ and $B$,and identify the correct choice given in the answers: $(A)$ Duddell's thermo galvanometer is suitable to measure direct current only. $(B)$ Thermopile can measure temperature differences of the order of $10^{-3} {}^{\circ}C$.