In which of the following is the oxidation number of nitrogen zero?
Odpověď
(E)
N2
3
The separation of a mixture of calcium trioxocarbonate (lV) and sodium trioxocarbonate (IV) is most easily carried out by using the differences in their
Odpověď
(D)
solubility
4
When air is passed through a heated tube containing finely divided copper, the component that is absorbed in the process is
Odpověď
(C)
oxygen
5
What is the amount (in mole) of sodium trioxocarbonate (IV) in 5.3 g of the compound? (Na2CO3 = 106)
Odpověď
(A)
0.05
6
Which of the processes represented by the following equations has the greatest positive entropy change?
Odpověď
(A)
C6H3(l) → C6H 6(g)
7
Which of the following elements can from more than one acidic oxide?
Odpověď
(B)
Sulphur
8
CH2 = CH2 + H2SO4 → CH3 - CH2 -OSO3H. The reaction illustrated by the equation above is an example of
Odpověď
(D)
addition
9
Brass is an alloy of copper and
Odpověď
(C)
zinc
10
Which of the following formula is that of a dicarboxylic acid?
Odpověď
(D)
CH2(COOH)2
11
The products of the electrolysis of dilute sodium chlorid solution with platinum electrodes are
Odpověď
(A)
hydrogen and oxygen
12
Which of the following modes of motion is exhibited by the particles of a solid?
Odpověď
(D)
Vibrational motion only
13
Which of the following statements is not correct? Group 7 elements
Odpověď
(D)
have relatively low ionization potentials
14
In which of the following are the substances arranged in their correct order of increasing melting point?
Odpověď
(C)
Sulphur, sodium chloride, diamond
15
A compound which liberates carbon (IV) oxide from a hydrogentrioxocarbonate (lV) could have the molecular formula
Odpověď
(C)
HCOOH
16
CH4(g) + 2O2(g) → 2H2O(l) + CO2(g) ∆H = 890KJ mo-1 ∆H in the reaction represented by the equation above is the enthalpy of
Odpověď
(B)
combustion
17
Consider the reaction represented by the equation below: H2(g) + 12(s) ⇌ 2HI(g) ∆H negative. Which of the following takes place when the temperature of the reaction vessel is decreased?
Odpověď
(E)
the yield of hydrogen iodide increases
18
2NaNO3 → 2NaNO2 + O2. From the equation above, what is the volume of oxygen produced at s.t.p. when 8.5g of 2NaNO3 is heated until no further gas is evolved? (2NaNO3 = 85, molar volume of gases at s.t.p. = 22.4dm3)
Odpověď
(A)
1.12dm3
19
Esterification of propane 1,2,3-triol and unsaturated higher carboxylic acids will produce
Odpověď
(C)
methly-propanoate
20
The ratio of reactants to products is 1: 3: 2 in the reaction represented by the equation below: N2,/SUB> (g) → 2NH3(g) which of the following law is demonstrated by this?
Odpověď
(C)
Gay Lussac's law
21
In the redox reaction represented by the following equation: Cu2+aq + Zn(s) → Cu(s) + Zn2+
Odpověď
(B)
copper (ll) ions are reduced to copper atoms
22
When starch undergoes complete enzyme-catalyzed hydrolysis, the resulting product is
Odpověď
(A)
glucose
23
Which of the reactions represented by the following equations will take place at room temperature?
Odpověď
(D)
2Na + 2H2O → 2NaOH + H2
24
Which of the following is not a direct petroleum product?
Odpověď
(D)
Vaseline
25
How many principal electronic shells has an atom whose electronic configuration is shown below? 1s22s22p63s1
Odpověď
(C)
3
26
Which of the following properties is not characteristic of electrovalent compounds?
Odpověď
(C)
high vapour pressures
27
Compounds that have the same molecular formula but different structures are said to be
Odpověď
(D)
isomeric
28
In which of the following crystals are the particles held by van der Waal's forces only?
Odpověď
(D)
Iodine
29
A current of 4.0 amperes was passed through copper (ll) tetraoxosulphate (IV) solution for one hour using copper electrodes. What was the mass of copper deposited? (Cu = 64, 1F = 96500 C)
Odpověď
(B)
4.8g
30
When a crystal was added to its solution, it did not dissolve and the solution remained unchanged, showing that the solution was
