What is formed when carbon monoxide reacts with $Cl_2$ in the presence of sunlight?

The magnetic needle of a tangent galvanometer is deflected at an angle $30^{\circ}$ due to a magnet. The horizontal component of the Earth's magnetic field is $0.34 \times 10^{-4} \text{ T}$,which is along the plane of the coil. The magnetic field due to the magnet is:

The number of moles of electrons required to deposit $36 \ g$ of $Al$ from an aqueous solution of $Al(NO_3)_3$ is (At. wt. of $Al = 27$)

The period of a simple pendulum,whose bob is a hollow metallic sphere,is $T$. The period is $T_1$ when the bob is filled with sand,$T_2$ when it is filled with mercury,and $T_3$ when it is half-filled with mercury. Which of the following is true?

If $\log _{0.3}(x - 1) < \log _{0.09}(x - 1),$ then $x$ lies in the interval

$\frac{1}{1 \cdot 3} + \frac{1}{2 \cdot 5} + \frac{1}{3 \cdot 7} + \frac{1}{4 \cdot 9} + \ldots$ is equal to