Which of the following is not a lateral meristem?

The quadratic equations $x^2 - 6x + a = 0$ and $x^2 - cx + 6 = 0$ have one root in common. The other roots of the first and second equations are integers in the ratio $4 : 3$. Then the common root is

Fluorosis disease is caused due to the reaction of ...... with excess of fluoride in the body.

$2 \pi - \left(\sin ^{-1} \frac{4}{5} + \sin ^{-1} \frac{5}{13} + \sin ^{-1} \frac{16}{65}\right)$ is equal to

We consider the radiation emitted by the human body. Which of the following statements is true?

Thermite is a mixture of $X$ parts of ferric oxide and $Y$ parts of aluminium powder. What are $X$ and $Y$ respectively?