Secondary one

The percentage of water of crystallization in hydrated sodium carbonate (Na₂CO₃.10H₂O)..............

 ( Na = 23 , C = 12 , O = 16 , H = 1 )

7.14%
62.93%
25.36%
14.52%

When 56.36% of phosphorous is combined with 43.64% of oxygen, a compound with the formula …………

 ( P = 31 , O = 16 )

a.     P₂O₅                            b.    PO₂                           c.     P₂O₄                             d.    P₂O₃

a
b
c
d

The total percentage of aluminum in aluminum sulfate is .............(Al = 27 , S = 32 , O = 16 )

7.89%
20.8%
15.79%
36%

                           Two balloons have the same size in (STP) one is filled with helium gas, 

and the other with argon gas, which of the following expressions correctly expresses them?

a) A helium balloon contains more atoms than an argon balloon
b) A helium balloon contains fewer atoms than an argon balloon
c) A helium balloon contains the same number of atoms as an argon balloon
d) A helium balloon has a mass greater than that of an argon balloon

The molar mass of the compound, Al₂(SO₄)₃.18H₂O is:

(Al = 27 , S=32,O=16 , H=1)

666 g/mole
394.4 g/mole
110,900 g/mole
561.2 g/mole

The number of moles of oxygen needed for the reaction of 5.5g of ammonia …………mole, according to the unbalanced equation:

NH₃+O₂  NO₂ +H₂O

Note that: (N = 14 , O = 16 , H = 1)

1
0.56
5.4
0.24

                                                             A student takes 2 g samples of calcium carbonate and adds them to 20 cm³ samples of dilute hydrochloric acid at different temperatures. She measures how long it takes for the effervescence to stop. Which apparatus does she use?

A
B
C
D

112)When burning C₃H₆ propene, the oxygen coefficient is ............

 

3
9
13
15

55.58 g/mol
28 g/mol
63 g/mol
70.9 g/mol

 vanadium oxide compound is found to be 68% vanadium and.               32% oxygen by mass. What is the empirical formula of this compound? Take the atomic masses of vanadium and oxygen to be 51 and 16, respectively.

V2O3
V4O9
VO
VO2

Number of atoms of elements contained in 0.3mol of calcium bicarbonate?

a
b
c
d

                                                           In the following equation: 2Mg+O₂→2MgO, if 12g of magnesium burns in a vessel containing 32g of oxygen, the mass of magnesium oxide produced is............... g (Mg = 24 , O = 16)

80
40
20
120

Which of the following sentenc is

        not correct about 16 g of methane CH₄? (C = 12 , H = 1 )

a. It represent one mole of methane

b. It represent methane which contains 12 g of carbon

c. It contains 9.63 × 10²⁴ molecule of methane

d. It contains 2.4 × 10²⁴ atom of hydrogen

a
b
c
d

0.04
4
40
0.4

A student was provided with only a thermometer, a stopwatch and a beaker. What could the student measure? 

A) 10.5g solid and 24.8cm³ liquid

B) 10.5g solid and 25°C

C) 24.8cm³ liquid and 45 seconds

D) 25°C and 45 seconds

a
b
c
d

The mass of aluminum reacting with 20 g of sodium hydroxide is ……………g, according to the equation:

          2Al + 6NaOH                   2Na₃AlO₃ +3H₂

Note that: (Na = 23 , Al = 27 , O = 16 , H = 1)

4.5
27
6.7
10.5

From the following reaction:

CH₄ +4Cl₂ CCl₄ + 4HCl

The mass of CCl₄ produced by the reaction of 4.5g of methane in an abundance of oxygen gas is ................g.

Note that (C = 12 , Cl = 35.5 , H = 1)

0.47
43.31
0.43
67.2

Which of the following contains the largest number of moles?

(H=1 , N = 14 , O = 16 , C = 12 )

a.1 g of H₂               b. 2 g of N₂

c. 4 g of O₂              d. 11 g of CO₂

a
b
c
d

Which of the following is an application of the Avogadro principle?

a) 12.4L of oxygen gas contains the same number of molecules as 12.4L of hydrogen gas
b) One liter of chlorine gas contains the same number of atoms as a liter of sulfur dioxide
c) The volume occupied by 25 grams of methane gas is greater than the volume occupied by 2 grams of fluorine gas
d) The volume of 2 moles of methane is less than the volume of 2 moles of ammonia

Which of the elementary compounds has the least gram mass of its empirical formula?(C =12 , H=1)

 

a.    C₂H₄

 

b.    C₃H₆

 

c.     C₄H₁₀

 

d.    C₆H₆

a
b
c
d