Question

1.

Sodium oxide reacts with water to produce sodium hydroxide. Suppose 19.6 g of sodium oxide is combined with 30.8 g of water. When the reaction is complete, all the sodium oxide has been consumed. According to the law of conservation of mass, which is a true statement?

A.The mass of sodium hydroxide produced must equal 50.4 g.

B.The mass of sodium hydroxide produced plus the mass of unreacted water must equal 50.4 g.

C.The mass of sodium hydroxide produced must equal 19.6 g.

D.The mass of water consumed must equal 19.6 g.

E.The mass of unreacted water must equal 11.2 g.

2.

Which net ionic equation best represents the reaction that occurs when an aqueous solution of sodium nitrate is mixed with an aqueous solution of ammonium bromide?

A.NH₄Br(aq) + NaNO₃(aq) → NaBr(s) + NH₄NO₃(aq)

B.No net reaction occurs.

C.NH₄⁺(aq) + NO₃^–(aq) → NH₄NO₃(aq)

D.Na⁺(aq) + NH₄Br(aq) → NaBr(s) + NH₄⁺(aq)

E.Na⁺(aq) + Br^–(aq) → NaBr(s)

3.

Which of the following nuclides contains more protons than neutrons?

A. 1/1 H

B. 24/12 Mg

C. 34/ 16 S

D. 19/9 F

E. 4/2 He

Answer 1

Q1 Solution :- balanced reaction equation is as follows

Na2O + H2O ----- > 2NaOH

Now lets calculate the amount of the NaOH produced from the 19.6 g Na2O

(19.6 g Na2O *1 mol/ 61.979 g)*(2 mol NaOH/1mol Na2O)*(40 g /1mol NaOH)= 25.3 g NaOH

Lets calculate mass of water needed for reaction

(19.6 g Na2O *1 mol/ 61.979 g)*(1mol H2O/1mol Na2O)*(18.0148 g /1mol NaOH)= 5.7 g H2O

Therefore mass of water remain = 30.8g – 5.7 g =25.1 g

Hence mass of NaOH and unreacted H2O = 25.3 g +25.1 g = 50.4g

Statement B is correct statement that is B.The mass of sodium hydroxide produced plus the mass of unreacted water must equal 50.4 g. is the correct statement

Q2 correct answer is option B- No net reaction occurs

Because the reaction equation is as follows

NH4Br(aq) +NaNO3(aq) ------ > NH4NO3(aq) + NaBr(aq)

Both the products of the reaction are soluble therefore all are cancelled out as spectator ions and hence no net reaction remain.

Q3 Correct answer is option A – 1/1H

Because in 1/1H number of proton =1 and number of neutron =0

Therefore protons are more than neutrons.