The molarity of liquid $HCl$ with a density equal to $1.17 \ g/cc$ is: (in $M$)

In an experiment,it was shown that $10 \ mL$ of a $0.05 \ M$ solution of a chloride required $10 \ mL$ of a $0.1 \ M$ solution of $AgNO_3$. Which of the following will be the formula of the chloride ($X$ stands for the symbol of the element other than chlorine)?

$20 \ mL$ of $CO_2$ gas are passed over excess of red hot coke. The volume of $CO$ evolved is ............. $mL$.
$CO_{2(g)} + C_{(s)} \to 2CO_{(g)}$

The charge carried by $1 \text{ millimole}$ of $M^{n+}$ ions is $193 \text{ C}$. The value of $n$ is

Diatoms,microscopic organisms,are an abundant food source in the oceans producing carbohydrates from carbon dioxide and water by photosynthesis.
$6CO_2 + 6H_2O + \text{solar energy} o C_6H_{12}O_6 + 6O_2$
$A$ blue whale gains $75 kg$ of mass per day by feeding on krill. The whale must consume ten times this mass of krill each day. The krill must consume $10.0 kg$ of diatoms to produce $1.0 kg$ of krill. Assuming that the mass gain of a whale's life is due to the consumption of carbohydrates $(C_6H_{12}O_6)$,calculate the moles of $CO_2$ that must be used by the diatoms to produce the carbohydrates consumed by a blue whale in a day.

How many kilograms of $CaCO_3$ must be heated to obtain $56$ kilograms of $CaO$? [Atomic masses: $Ca = 40, C = 12, O = 16$]