There are two natural isotopes of hydrogen `(""^(1)H gt 99%: ""^(2)H lt 1)`. Chlorine also has two natural isotopes `(""^(35)Cl=75:""^(37)Cl=25%)`. How many different molecules of HCl are possible? Arrange then in the decreasing order of their relative abundance.

Atomic weight of ordinary hydrogen is 1.008. ordinary hydrogen contains two isotopes ""_(1)^(1)H and ""_(1)^(2)H . What is the weight percentage of ""_(1)^(2)H in ordinarry hydrogen?

1.78L of chlorine gas at STP is prepared by using 40% HCl by weight according to the following reaction- MnO_(2)+4HCl to MnCl_(2)+2H_(2)O+Cl_(2) . Find the volume of hydrochloric acid and mass of MnO_(2) requried to produce this amount of chlorine gas. [specific gravity of the HCl solution=1.12]

This question has statement I and Statement II. Of the four choices given after the statements, choose the one that best describes the two Statements. (1) Statement-I is true, Statement-II is true, Statement-II is a correct explanation of Statement-I (2) Statement-I is true, Statement-II is true,Statement-II is not a correct explanation of Statement-I (3)Statement-I is a true , Statement-II is false (4) Statement-I is false, Statement-II is true Statement-I: The HF_2^- ion exists in the solid state and also in the liquid state but not in aqueous solution. Statement-II: The magnitude of hydrogen bonds in between HF-HF molecules is weaker than that in between HF and H_2O molecules.

In the atmosphere, carbon dioxide is found in two forms, i.e., ^12CO_2 and ^14CO_2 . Plants absord CO_2 during photosynthesis in presence of chlorophyll, plants systhesise glucose 6CO_2 +6 H_2O rarr C_6H_12O_6 + 6O_2uarr Half life of ^14CO_2 is 5760 years. The analysis of wooden artifacts for ^14C and ^12C gives useful information for determination of its age. All living organisms, because of their constant exchange of Carbon dioxide with the surroundings have the same ratio of C-14 to C-12, i.e. 1.3xx10^-12 . When an organism dies, the C-14 in it keeps on decaying as follows: 6^14Crarr7^14N+(-1)^0e +Energy Thus, the ratio of C-14 and C-12 decreases with the passage of time. We can measure the proportion of C-14 in the remains of dead organism and determine how long ago it died. The method of carbon dating can be used to date anything made or organic matter, e.g., bone, skeleton, wood, etc. Using carbon dating, materials have been dated to about 50,000 years with accuracy. A piece of wood from an archeological source shows a C-14 activity which is 60% of the activity found in fresh wood today. The age of archeological sample will be: