20 cm\(^3\) of hydrogen gas are sparked with 20cm\(^3\) of oxygen gas in an endimoeter at 373k (100\(^0\)C) and 1 atmosphere. The resulting mixture is cooled to 298 K (25 oC) and passed over calcium chloride. The volume of the residual gas is
คำตอบ
(D)
10cm 3
3
For the reaction NH4NO2 \(\to\) N2 + 2H2O, calculate the volume of nitrogen that would be produced at S. T. P from 3.2 g of the dioxonitrate(iii)salt. (Relative atomic masses: N = 14, O = 16, H = 1)
คำตอบ
(D)
1. 12dm 3
4
A molar solution of caustic soda is prepared by dissolving
คำตอบ
(B)
40 g NaOH in 1000 g of water
5
Which among the elements 1. Carbon 2. Oxygen 3. Copper 4. Bromine 5. Zinc, will NOT react with either water or steam?
คำตอบ
(B)
2 and 3
6
Naphthalene when heated melts at 354 K (81 oC). At this temperature the molecules of naphthalene
คำตอบ
(E)
become mobile as the inter molecular forces are broken
7
The ratio of the number of molecules in 2g of hydrogen to that in 16g of oxygen is
คำตอบ
(A)
2:1
8
The balanced equation for the reaction of tetraoxosulphate(VI)acid with aluminium hydroxide to give water and aluminium tetraoxosulphate(VI) is
คำตอบ
(B)
3H2SO4 + 2Al(OH)3 \(\to\) 6H2O + Al2(SO4)3
9
Which of the following mixtures would result in a solution of pH greater than 7?
คำตอบ
(A)
25.00 cm3 of 0.05 M H2SO4 and 25.00cm3 of 0.50 M Na2CO3
10
In which of the following reactions does hydrogen peroxide act as a reducing agent?
คำตอบ
(D)
PbO2 + 2HNO3 + H2O2 \(\to\) Pb(NO3)2 + 2H2O + O2
11
For the reaction 2Fe3+ 2I- \(\to\) 2Fe2+ + I2, which of the following statements is TRUE?
คำตอบ
(C)
I- is oxidized to I2
12
In dilute solution the heat of the reaction NaOH + HCl = NaCl + H2O is - 57.3kJ. Therefore the heat of the reaction 2NaOH + H2SO4 \(\to\) Na2SO4 + 2H2O is
คำตอบ
(D)
- 114.6 KJ
13
Which of the following methods may be used to prepare trioxonitrate (V) acid (nitric acid) in the laboratory?
คำตอบ
(C)
Heating sodium trioxonitrate (V) with tetraoxosulphate (VI) acid
14
Lime - water, which is used in the laboratory for the detection of carbon(iv)oxide is an aqueous solution of
คำตอบ
(A)
Ca(OH)2
15
An element that can exist in two or more different structural forms which possess the same chemical properties is said to exhibit.
คำตอบ
(E)
allotrophy
16
Sulphur
คำตอบ
(C)
burns with a blue flame
17
Which of the following statements is NOT true of carbon monoxide?
คำตอบ
(B)
CO is readily oxidized at room temperature by air to form CO2
18
From the reactions : ZnO + Na2O \(\to\) NaZnO and ZnO + CO2 \(\to\) ZnCO3 it may be concluded that zinc oxide is
คำตอบ
(D)
amphoteric
19
An example of a neutral oxide is
คำตอบ
(D)
CO
20
3Cl2 + 2NH3 \(\to\) N2 + 6HCl. In the above reaction, ammonia acts as
คำตอบ
(A)
a reducing agent
21
In the Haber process for the manufacture of ammonia, finely divided iron is used as
คำตอบ
(C)
a catalyst
22
The hybridization of the carbon atom in ethyne is
คำตอบ
(D)
sp
23
An organic compound with a vapour density 56.5 has the following percentage composition:C =53.1% N = 12.4%, O = 28.3%, H = 6.2%. The molecular formula of the compound is
Relative atomic masses: N = 14, O = 16, C = 12, H = 1 )
คำตอบ
(D)
C5H7O2N
24
When the kerosene fraction from petrol is heated at high temperature, a lower boiling liquid is obtained. This process is known as
คำตอบ
(D)
cracking
25
Alkaline hydrolysis of naturally occurring fats and oils yields
คำตอบ
(B)
soaps and glycerol
26
Which of the following statements is INCORRECT?
คำตอบ
(E)
calcuim carbide will react with water to form any alkyne
27
Which of the following statements is NOT correct about all four of the acids: HBr, HNO3, H 2CO3 and H2SO4? They
คำตอบ
(A)
dissolve marble to liberate CO
28
If the cost of electricity required to deposit 1 g of magnesium is N5.00, how much would it cost to deposit 10g of aluminium?
คำตอบ
(D)
N66.67
29
Nitrogen can best be obtained from a mixture over oxygen and nitrogen by passing the mixture over
คำตอบ
(D)
heated phosphorus
30
Water is said to be 'hard' if it
คำตอบ
(C)
froms an insoluble scum with soap
31
Sodium hydroxide (NaOH) pellets are
คำตอบ
(A)
deliquescent
32
Alkanes
คำตอบ
(C)
contain only carbon and hydrogen
33
If an excess of a liquid hydrocarbon is poured into a jar of chlorine, and the sealed jar is then exposed for several hours to bring sunlight, all the chlorine gas is consumed. The hydrocarbon is said to have undergone
คำตอบ
(D)
a substitution reaction
34
The function of conc. H2SO4 in the esterification of ethanoic acid with ethanol is to
คำตอบ
(C)
act as a catalyst
35
A piece of sea shell, when dropped into a dilute solution of hydrochloric acid, produces a colourless, odourless gas which turns clear limewater milky. The sea shell contains
คำตอบ
(C)
calcium carbonate
36
Which of the following electrodes is used in electrolysis of bauxite (Al2O3) in molten cryolite?
คำตอบ
(B)
Carbon electrodes
37
An aqueous solution of a metal salt, M, gives a white precipitate with NaOH which dissolves in excess NaOH. With aqueous ammonia, the solution of M also gives a white precipitate which dissolves in excess ammonia. Therefore cartion in M is
คำตอบ
(A)
Zn ++
38
At S. T. P how many litres of hydrogen can be obtained from the reaction of 500 cm\(^3\) of 0.5 M H\(_2\)SO\(_4\) with excess zinc metal?
(Gram molecular volume of H\(_2\) = 22.4 dm\(^3\))
คำตอบ
(D)
5. 6 dm 3
39
The solubility curves of four substances are shown in the figure above. Which of the four substances would crystallize from a saturated solution cooled from 353K(80oC)to 323K(50C)?
คำตอบ
(D)
R and S
40
Which of the curves shown in the figure given represents the relationships between the volume(V) and pressure(P) of an ideal gas at constant temperature
