If water sample are taken from sea, rivers or lake, they will be found to contain hydrogen and oxygen in the approximate ratio of `1 : 8`. This indicates the law of :

A radioactive isotope X with half-life of 693xx10^(9) years decay to Y which is stable. A sample of rock from of the moon was found to contain both the elements X Y in the mole ratio 1:7 . What is the age of the rock ? a) 2.079xx10^(12) years b) 1.94xx10^(10) years c) 1.33xx10^(9) years d) 10^(10) years

In water molecule the ratio by mass in which hydrogen and oxygen react is 1 : 8, Calculate the ratio by number of atoms in water molecules.

An oxygen cylinder of volume 30 litres has an initial gauge pressure of 15 atm and a temperature of 27 ^@C . After some oxygen is withdrawn from the cylinder, the gauge pressure drops to 11 atm and its temperature drops to 17 ^@C . Estimate the mass of oxygen taken out of the cylinder ( R= 8.31 J mol^-1 K^-1 ’, molecular mass of O_2 = 32 u)

A jar contains mixture of hydrogen and oxygen gases in the ratio 1: 5 . What is the ratio of mean translational kinetic energy of hydrogen and oxygen molceule?

Three water samples namely river water, untreated sewage water and secondary effluent discharged from a sewage treatment plant were subjected to BOD tcsl. The samples were labelled A, B and C: but the laboratory attendant did not note which was which, The BOD values of the three samples A, B and C were recorded as 20mg/L. 8mg/L and 400mg/L. respectively. Which sample of the water is most polluted? Can you assign the correct label to each assuming the river water is relatively clean?

A message was transmitted from boat which returned to the sender after reflection from the bottom of the sea in 0.8 s. If the velocity of sound in water is 1500ms^-1 then find the depth of sea.

A 1.025 g sample containing a weak acid HX (mol. Mass=82) is dissolved in 60 mL. water and titrated with 0.25 M NaOH. When half of the acid was neutralised the pH was found to be 5.0 and at the equivalence point the pH is 9.0. Calculate mass precentage of HX in sample :

Common salt obtained from sea-water contains 8.775% Na Cl by mass. The number of formula units of NaCl present in 25 g of this salt is :

Bag I contains 3 red and 5 white balls while another bag II contains 1 red and 8 white balls. One ball is drawn at random from one of the bags and found to be \white. Find the probability that it was drawn from bag II.