1. Which of the following represents a qualitative observation? a) The substance

Question

1. Which of the following represents a qualitative observation? a) The substance is a powder and is red in colour. b) The mass of the metal is 3.57 g. c) The object occupies a volume of 5.0 mL d) Both (b) and (c). 2. An atom has a total of 11 electrons. The ground state electron configuration moving out from the nucleus, is: a) 6)6)6) 2) 0 6)-4) Which of the following atoms has the electron orbit arrangement "2) 5)"? a) Fe c) F 3. b) Cl d) N 4. Consider the formation of one formula unit of Na3P from neutral atoms. In the process each Na atomelectrons) and each a) gains 3, loses 1 c) loses 3, gains 3 P atom_ electron(s) b) loses 3, gains 1 d) loses 1, gains 3 5. Choose the reaction that represents a single displacement reaction. a) Pb(NO3)2ag) + 2Kl(aa) Pbl2) KNO3(a) b) 2Als)3Fe(NO3)3(a) 3Fes) 2AI(NO3)3/a) 6. The substance least soluble in water is: a) HCI b) CaSO4 c) NaHCOs d) LioH 7. The net-ionic equation for the reaction between lead (II) nitrate solution and potassium chloride solution is: a) Pb(s) + 2Cl(g) >PbCl28) Which of the following represents the number of particles in one mole of a substance? a) 6.02 x 1023 8. b) It depends on the type of substance d) All of the above are correct c) 1.01 x 103 Copvright 2007, Durham Continuing Education

Explanation / Answer

1)

Qualitative observation indicates the composition of the substance. Among all the options the substance is a powder and is red in colour.

Answer : A

2)

11 electrons means the electronic configuration is 1s2 2s2 2p6 3s1.

Answer : d

3)

the electronic configuration is given by 1s2 2s2 2p3 and it is the configuration of atom N.

Answer : d

4)

In the formation of Na3P from the neutral atoms as below.

Na3P ------> 3Na+ + P3-

3Na ------> 3Na+ + 3e- (3 Na atoms loses 3e-)

P + 3e- -----> P3-

So each Na atom loses 1e- and each P atom gains 3e-

5)

Among all the reactions the following reaction is single displacement reaction since Al replaces the Fe from the given compound.

2 Al(s) + 3 Fe(NO3)3 (aq) --------> 3 Fe(s) + 2Al(NO3)3(aq)

Answer : b

6)

CaSo4 is a stable salt which has the solubilty product value very low so the precipitate least soluble in the water.

Answer : b

7)

Molecular equation

Pb(NO3)2 (aq) + 2 KCl(aq) ------> PbCl2(s) + 2 KNO3(aq)

Ionic equation

Pb+2(aq) + 2 NO3-(aq) + 2 K+(aq) + 2Cl-(aq) ------> PbCl2(s) + 2K+(aq) + 2 NO3-(aq)

Net ionic equation

Pb+2(aq) + 2Cl-(aq) -------> PbCl2(s)

Answer : d

8)

1 mole of any substance have 6.023 * 10^23 particles of the substance

Answer : a

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