3 sec - quiz 1

Fe₃O₄ + H₂ -----------> Fe + H₂O

what is the sequence of the cofficient after balancing ?

• 1 , 4 , 3 , 4

• 1 , 1 , 2 , 3

• 1 , 2 , 2 , 3

• 1 , 3 , 3 , 2

The mass of 0.25 mol of magensuim chloride equals ..........

[Mg = 24 ,Cl = 35.5 ]

• 23.75

• 24

• 23.2

• 23

Calculate the molar mass of: HNO₃

[ O = 16 , H = 1,N= 14]

• 63 g

• 63 u

• 62 g

• 62 u

Number of atoms in 1.25 mol of NO₂­ equals .......

• 22.575 x 10²³ atoms

• 18.06 x 10²³ atoms

• 3.75 atoms

• 3 atoms

The molar mass of ammonia gas (at STP) equals the mass of each of the following except

[N = 14 , H = 1]

• 6.02 x 10²³ molecules.

• 22.4 L

• 17 g

• 3 x 6.02 x 10²³ atoms

The volume of 12.04 x 10²³ molecules of hydrogen gas (at STP) equals ……………

• 89.6 L

• 44.8 L

• 22.4 L

• 2L

Which of the following diagrams expresses an endothermic reaction that has the least ∆H value (with positive sign) ? …………..

• a

• b

• c

• d

The volume of hydrogen which is required to produce 11.2 L of water vapour (at STP) equals ....

• 68.2 L

• 11.2 L

• 44.8L

• 22.4L

2 mol of nitrogen gas N₂ combines with 6 mol of hydrogen gas H₂ to form each of the following, except ……….. [N = 14 , H = 1]

• 4 mol of NH₃

• 78 g of NH₃

• 4x6.02 x 10²³ molecules of NH₃

• 17 g of NH₃

On dissolving 1 mol of sodium sulphate in water completely, the total number of ions equals ………….

• Avogadro's number.

• 2 x Avogadro's number.

• 3 x Avogadro's number.

• 4 x Avogadro's number.