Some basic concepts of chemistry

Which of the following statement is INCORRECT

• protium has no neutron

• C14 is used for finding age of old wooden objects

• Ca-40 and Ar-50 are isotopes

• Ca-40 and Ar -40 are isobars

What will be the molarity of a solution, which contains 5.85 g of NaCl(s) per

500 mL?

• 4

• 20

• 0.2

• 2

The number of atoms present in one mole of an element is equal to Avogadro

number. Which of the following element contains the greatest number of

atoms?

• 4g He

• 46g Na

• 0.4g Ca

• 12g He

What is the mass percent of carbon in carbon dioxide?

• 40

• 27

• 32

• 10

The empirical formula and molecular mass of a compound are CH2O and

180 g respectively. What will be the molecular formula of the compound?

• C2H4O2

• HCHO

• C6H12O6

• CH3COOH

Which of the following reactions is not correct according to the law of

conservation of mass.

(i)

(ii)

(iii)

(iv)

• 2Mg(s) + O2(g) --> 2MgO(s)

• C3H8(g) + O2(g) -->CO2(g) + H2O(g)

• P4(s) + 5O2(g)--> P4O10(s)

• CH4(g) + 2O2(g) --> CO2(g) + 2H2O (g)

For aq sol, which is true

• 1m=1M

• 1m is less concentrated than 1M

• 1m is more concentrated than 1M

• Data insufficient

Which is used to Express amount of mercury vapour in atmosphere

• M

• m

• Mole fraction

• ppm

What vol of air is needed for complete combustion of 32g methane

• 2*22.4l

• 4*22.4l

• 20*22.4l

• 22.4l

If 20 litre nitrogen gas reacts with 30 litre hydrogen gas to give ammonia, the volume of product formed is

• 40

• 20

• 50

• 30