Which group of plants was the first to exist on Earth?

Which of the following statements is consistent with halophiles?

The angle between the lines whose direction cosines are $\left(\frac{\sqrt{3}}{4}, \frac{1}{4}, \frac{\sqrt{3}}{2}\right)$ and $\left(\frac{\sqrt{3}}{4}, \frac{1}{4}, \frac{-\sqrt{3}}{2}\right)$ is:

The reading of the ammeter in the circuit shown will be: (in $A$)

The potential difference $V$ and the current $i$ flowing through an instrument in an $ac$ circuit of frequency $f$ are given by $V = 5 \cos \omega t \text{ volts}$ and $i = 2 \sin \omega t \text{ amperes}$ (where $\omega = 2\pi f$). The power dissipated in the instrument is....$W$

Two liquids $A$ and $B$ are at $32\,^{\circ}C$ and $24\,^{\circ}C$. When mixed in equal masses,the temperature of the mixture is found to be $28\,^{\circ}C$. Their specific heats are in the ratio of: