If $p \Rightarrow (q \vee r)$ is false,then the truth values of $p, q, r$ are respectively

Arrange $NH_4^+$,$H_2O$,$H_3O^{+}$,$HF$,and $OH^{-}$ in increasing order of acidic nature.

Which of the following is an amphoteric oxide?

The position vector of a point lying on the line joining the points whose position vectors are $\hat{i}+\hat{j}-\hat{k}$ and $\hat{i}-\hat{j}+\hat{k}$ is:

$A$ stunt man jumps his car over a crater as shown (neglect air resistance).

An ideal heat engine operates on a Carnot cycle between $227\,^{\circ}C$ and $127\,^{\circ}C$. It absorbs $6 \times 10^4\, \text{cal}$ at the higher temperature. The amount of heat converted into work is equal to: