Que26

The number of oxygen atoms 18 atoms of oxygen ( answer D)

calculation

count the number of oxygen atoms in Ba(ClO3)2

that is = 3 x2 = 6 atoms

then multiply by 3 since there are 3 molecules of Ba(ClO3)2

that = 6 x3 = 18 atoms of oxygen

Que 27

The number of atoms of oxygen is 18 atoms of Oxygen ( answer D)

calculation

Step 1: count the number of oxygen atoms in Fe(NO3)2

that is = 3 x2 = 6 atoms of Oxygen

Step 2: multiply by total number of Fe(NO3)2 molecules ( 3 molecules)

that is , 6 x3 = 18 atoms of oxygen

question 28

The coefficient in front of H2O is 4 ( answer 8)

Explanation

Balance the equation

= 3 Fe + 4 H2O → Fe3O4 + 4 H2

therefore the coefficient in front of H2O = 4

que 29

The balance chemical equation is

Zn + 2HCl→ ZnCl2 +H2 ( answer D)

Explanation

Zn + 2HCl→ ZnCl2 + H2 is balanced since it obey the law of mass conservation.

Que 30

The coefficient in front of HNO3 is 2 ( answer B)

Explanation

balance the equation of N2O5 + H2O→ 2HNO3

Therefore the coefficient in front of HNO3 is 2

Que 31

The number of atoms of Hydrogen is 10 atoms ( answer D)

Calculation

Step 1: count the number of H atoms in CH3CH2O

= 3 +2= 5 atoms

Step 2: multiply 5 atoms by 2 ( coefficient in front of CH3CH2O)

= 5 atoms x 2 = 10 atoms

Ques 32

The moles of Oxygen gas needed is 2 moles ( answer C)

Explanation

= 4 Li +O2 → 2Li2O

The mole ratio of Li :O2 = 4:1

therefore the moles of Oxygen = 8 moles x1/4 = 2 moles

Que 33

The limiting reactant is HCl and 5.8 moles of H2 can be formed

Explanation

to determine the limiting reagent

Al : AlCl3 is 2 :2 = 1:1 therefore the moles of AlCl3 = 4.5 moles

HCl: AlCl3 = 6:2 therefore the moles of Al2Cl3 = 11.5 x2/6= 3.8 moles

therefore HCl is the limiting reagent since it is totally consumed

moles of HCl formed

The mole ratio of HCl: H2 = 6:3 therefore the moles of H2 = 11.5 x 3/6 = 5.8 moles

que 34

The grams of oxygen gas = 20.6 g O2( answer A)

explanation

calculate the moles of LiClO3

= 38.7 g / 90.38 g/mol=0.428 moles

by use of mole ratio of of LiClO3: O2= 2:3 the moles of O2

= 0.428 x3/2=0.642 moles

mass =moles x molar mass

= 0.642 moles x 32 g/mol= 20.6 g O2

Ques 35

The grams of silicon nitride that can be formed is 35.88 g( answer C)

calculation

find the moles of nitrogen

= 14.33 g/ 28 g/mol=0.512 moles

N2: Si3N4 is 2:1 the moles of SiN4

= 0.512 moles x 1/2=0.256 moles

find the grams of Si3N4

= 0.256 moles x 140.28 g/mol = 35.91 g which is around 35.88 (answer c)

Que 36

The grams of phosphorus trichloride that can be formed is is 176 g ( answerB)

calculation

moles of P4 = 62.4 g / 123.90 g/mol =0.504 moles

moles of cl2 = 136.2/71 g/mol =1.918 moles

P4 : PCl3 is 1:4 therefore the moles of PCl3 = 0.504 x 4=2.016 moles

Cl2 : PCl3 is 6:4 therefore the moles of PCl3= 1.918 moles x 4/6=1.279 moles

Cl2 is the limiting reagent therefore the moles of PCl3 = 1.279 moles

find the mass of PCl3

= 1.279 moles x 137.33 g/mol =176 g

Que 37

The truth about physical properties is The physical properties include properties like density, melting point, and ductility

Explanation

Physical properties are be measure or observed without changing the composition of matter.

Que 38

The coefficient that must be added to balance the equation are

2,1,1,2 ( answer c)

Explanation

The mass of the product is equal to mass of the reactant when the equation is balanced..

que 39

The chemical equation that violates the law of mass conservation of mass is K2SO4 +2Ca(NO3)2→ 2KNO3 + 2CaSO4 ( answer A)

Explanation.

K2SO4 + 2Ca(NO3)2 → 2KNO3 + 2CaSO4 violate this law because the mass of reactant is not equal to mass of product.

For example in )2 there is 16 atoms of aO2 in reactant side while at product side they are 14 atoms.

Que 40

The double replacement reaction is

K2S + CoCl2→ 2KCl + COS ( answer A)

Explanation

in Double replacement the cation and anion of the two reactant switch places to form new compound.

NB: find question 41- 45 in the attachment below ( the answer was long could not all fit.)