Chemistry Past Questions and Answers

Which of the following reactions are always exothermic? 1. Neutralization Il. Decomposition III. Combustion

A I and II only
B I and III only
C II and IIl only
D I, II and III

Question 1637:

Which of the following standard conditions is not correct about energy changes?

A Standard temperature is 298K
B B. Standard pressure is 1 atm
C Concentration of solution must be 1 mol/dm\(^3\)
D ΔH at 298 K is the activation energy

Question 1638:

f 5.0 cm\(^-3\) of 0.200 mol dm(^-3\) Na\(_2\)CO\(_3\) was diluted to 250cm(^-3\) solution, what would be the concentration of the resulting solution?

A 0.004 mol dm(^-3\)
B 0.020 mol dm(^-3\)
C 0.200 mol dm(^-3\)
D 0.400 mol dm(^-3\)

Question 1639:

The initial volume and pressure of a given mass of gas is V and 3.P. What is its pressure if its volume is increased to 2V at constant temperature?

A 3 P
B 2P
C \(frac{3}{2}\) P
D \(frac{2}{3}\) P

Question 1640:

What volume of oxygen at s.t.p is required to burn completely 7.5 dm\(^3\) of methane according to the following equation?
CH\(_4\) \(_g\) + 20\(_2\) \(_g\) → CO\(_2\) \(_g\) + H\(_2\)O\(_g\)

A 3.75 dm\(^3\)
B 7.59 dm\(^3\)
C 15.0 dm\(^3\)
D 30.0dm\(^3\)