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I'm not an expert teacher or lecturer of chemistry. I was only a student from SMA NEGERI 15 SURABAYA who had been one of the Bronze Medalist Participants of Olimpiade Sains Nasional X (2011) of Chemistry In Manado, North Sulawesi, 11 - 16 September 2011 and graduated in 2012. Now, I'm studying at Universitas Airlangga in Surabaya, Indonesia. I do love chemistry and I would like to help them who had difficulties in studying chemistry. That's why, please understand me if you found some misconcepts in my entries. Suggestions are always necessary in order to develop this blog. And I'm sorry because my English isn't so well.

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Thursday, December 31, 2009

The Final Semester 1 Test of Chemistry.

Hey! I wanna share with you about my final-first-semester-exam, and I hope this article will be useful for you :D

I’m sorry before because my English is not good. :P

1. X atom has atomic number 19, that element in the periodic table is situated on…

a. Period 2, Group IA

b. Period 3, Group IA

c. Period 4, Group IA

d. Period I, Group IVA

e. Period II, Group IVA

Answer: 19 -> [Ar] 4s1 (Electron configuration which based on quantum number’s
theory) or (2,8,8,1) (Electron configuration which based on Niels Bohr).
It means, this element is located on Period 4 and Group IA. So the answer is

2. Which of the following sets of quantum numbers is not allowed?

a. n=4, l=2, m=0, s=-1/2

b. n=4, l=1, m=3, s=+1/2

c. n=3, l=2, m=-2, s=-1/2

d. n=2, l=1, m=0, s=+1/2

e. n=4, l=2, m=-1, s=-1/2

Answer: You know the formulas of Quantum Number? Okay, I will explain you
one by one:
n : It states the amount of the shells of the atom.
l : It states the shape of an orbital, the amount of the sub-shell. (We
call it as Azimuthal). The formula of this Quantum Number is
m : It states the amount of orbital of an atom. (We call it as Magnetic).
The formula is –l till +l.
s : It states the direction of electron in its orbital. (We call it as Spin).
And the formula of this Quantum Number is +1/2 or -1/2.

So, the answer is B, because of the (m). Why?
Because the (l) value is 1 so, the value of (m) which allowed is -1 until +1

3. The following compound pair that has covalent bond is…
a. KCl and HCl

b. H2S and K2S

c. PCl3 and FeCl3

d. CH4 and NH3

e. H2O and Na2O

Answer: You have to remember this: Ionic bond is a bond that occurs between Metal
Element and Non-metal element; Covalent bond is a bond that occurs between
2 or more Non-metal element; Metallic bond is a bond that occurs between 2 or
more Metal Element.
KCl -> Ionic Bond

HCl -> Covalent Bond

H2S -> Covalent Bond

K2S -> Ionic Bond
PCl3 -> Covalent Bond
FeCl3 -> Ionic Bond

CH4 -> Covalent Bond

NH3 -> Covalent Bond

H2O -> Covalent Bond

Na2O -> Ionic Bond.
So, the answer is D

4. Which groups that consist of polar compounds?

a. HCl, HBr, NH3, H2O

b. CO2, Cl2, Br2, H2

c. H2, O2, CO, CO2

d. MgO, NH3, CO, CO2

e. SO2, Cl2, N2, NH3

Answer: Intramolecular force is a force between atoms in a molecule. Nah, A molecule will be stated as a polar molecule if it has one or more lone pair.
Mmm would you like to learn about Intermolecular force by yourself? Because
the answer is A.

5. The following pairs of compounds which both have hydrogen bond are…

a. HF and H2O
b. HF and HI

c. HBr and H2O

d. HCl and HBr

e. NH3 and HI

Answer: In the X grade, we know that the molecules that have hydrogen bond are HF, H2O, and NH3. So the answer is A

6. The compound that have sp3 hybrid orbital has the shape of…

a. Trigonal planar

b. Tetrahedral

c. Trigonal bipyramidal

d. Octahedral

e. Linear

Answer: sp -> Linear; sp2-> Trigonal planar; sp3 -> Tetrahedral; sp3d -> Trigonal bipyramidal; sp3d2 -> Outer Octahedral; d2sp3 -> Inner Octahedral.

So, the answer is B.

7. Reaction of Sulfur trioxide preparation takes place at certain temperature and pressure.

If the reaction which occurs is SO2(g) + O2(g) -> SO­3(g), then gases volume ratio of

This reaction respectively is…

a. 1 : 1 : 1

b. 1 : 1 : 2

c. 1 : 2 : 3

d. 2 : 2 : 2

e. 2 : 1 : 2

Answer: SO2(g) + O2(g) -> SO3(g). Okay, we already learned it before on my previous

Article. But don’t worry, I will explain that lesson in here :D.
The amount of S in the left side is 1 and the amount of S in the right side is
1 too, so we don’t have to balance it. But how about the O???
The amount of O in the left side is 4 and the amount of O in the right side is 3
so what will we do to balance the O??
Aaahhh You were right!! Time SO2 with 2, O2 with 1, and the SO3 with 2. :D

Now let’s see our equation now:
2SO2(g) + O2(g) -> 2SO3(g)

So the ratio is 2 : 1 : 2, the answer is E ! :D

8. The statement of element mass ratio in a compound is constant was expressed by…

a. Amedeo Avogadro.

b. Proust.

c. John Jacob Berzellius.

d. Lavoisier.

e. John Dalton.

Answer: Avogadro : Express that the coefficient in a molecule equals to its mol in the
same temperature and pressure.

Proust : Element mass ratio in a compound is constant.
Berzellius : He set the old version of periodic table.

Lavoisier : The mass before reaction equals to the mass after reaction.
Dalton : He stated that atom is the smallest particle that indestructible and

So the answer is B.

9. The volume of 16 gram Sulfur dioxide at 27oC and 1 atm is…

a. 2.10 liter

b. 3.25 liter

c. 4.20 liter

d. 5.25 liter

e. 6.15 liter

Answer: PV = nRT

The Mr of Sulfur dioxide is 64, The Temperature is 300K and The pressure is
1 atm, So:

1 * V = 16/64 * 0.082 * 300

V = 6.15 liter.
So the answer is E

10. What volume will 2.80 gram of N2 occupy at STP ?

a. 2.240 liter

b. 5.600 liter

c. 11.20 liter

d. 22.40 liter

e. 44.80 liter

Answer: PV = nRT

Because the volume is occupied at STP so the Molar Volume is 22.4 liter/mol
and we can change this formula into: V = n*Vm

N = m/Mr

2.80 gram/ 2*14 (Remember, The Ar of N is 14) = 0.1 mol

V = 0.1 * 22.4
= 2.24 liter.

So the answer is A.

11. If Avogadro constant = L, and the molar mass of ammonia gas is M g/mol, then in 10 mol of ammonia gas, the number of ….. molecules were found.

a. 10

b. 10L

c. L/10M

d. 10 ML

e. L/M

Answer: The amount of particle = The mol of the particle * Avogadro constant

X = n * L

X = 10L

PS: Avogadro Constant = 6.02x1023

So the answer is B.

12. The mass of nitrogen in a fertilizer containing 40 gram ammonium nitrate is…
a. 1.4 gram

b. 2.8 gram

c. 14 gram

d. 16.8 gram

e. 28 gram

Answer: Ammonium nitrate = NH4+ + NO3- = NH4NO3

Mr of NH4NO3 = 14 + (4*1) + 14 + (3*16)

= 80

The mass of N = n * Ar / Mr NH4NO3 * The mass of NH4NO3

= 2 * 14 / 80 * 40

= 14 gram

So, the answer is: C.

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