How many species are there in the genus $Homo$?

Compound $PdCl_4 \cdot 6H_2O$ is a hydrated complex; $1 \, m$ aqueous solution of it has a freezing point of $269.28 \, K$. Assuming $100 \%$ ionization of the complex,calculate the molecular formula of the complex ($K_f$ for water $= 1.86 \, K \, kg \, mol^{-1}$,freezing point of pure water $= 273.15 \, K$).

Based on lattice energy and other considerations,which one of the following alkali metal chlorides is expected to have the highest melting point?

What is the quantity of electricity (in Coulombs) required to deposit all the silver from $250 \ mL$ of $1 \ M \ AgNO_3$ solution?

If the product of the roots of the equation $(a + 1)x^2 + (2a + 3)x + (3a + 4) = 0$ is $2$,then the sum of the roots is:

Vapour pressure in $mm \ Hg$ of $0.1 \ mole$ of urea in $180 \ g$ of water at $25^{\circ} C$ is (The vapour pressure of water at $25^{\circ} C$ is $24 \ mm \ Hg$)