Bise Rawalpindi Solved Numerical of 9th Class Chemistry, Mcqs, Short Questions, and Long Questions.
Fundamentals of Chemistry Mcqs
Hair contains keratin proteins which are also present in nails and wool is an example of
- Biochemistry
- Inorganic chemistry
- Physical chemistry
- organic chemistry
The empirical formula for water is
- CO2
- HO
- H2
- H2O
A mixture that consists of different components is called
- homogeneous mixture
- heterogeneous mixture
- mixture
- dilute solution
i) Industrial chemistry deals with the manufacturing of compounds:
- A. in the laboratory
- B. on microscale
- C. on a commercial scale
- D. on the economic scale
ii) Which one of the following compounds can be separated by physical means?
- A. mixture
- B. element
- C. compound
- D. radical
iii) The most abundant element occurring in the oceans is:
- A. oxygen
- B. hydrogen
- C. nitrogen
- D. silicon
iv) Which one of the following elements is most abundant in the Earth’s crust?
- A. oxygen
- B. aluminum
- C. silicon
- D. iron
v) The third abundant gas found in the Earth’s atmosphere is:
- A. carbon monoxide
- B. oxygen
- C. nitrogen
- D. argon
vi) One AMU (atomic mass unit) is equivalent to:
- A. 1.66 x 10-24 mg
- B. 1.66 x 10-24g
- C. 1.66 x 10-24kg
- D. 1.66 x 10-23g
vii) Which one of the following molecules is not tri-atomic?
- A. H2
- B. O3
- C. H2O
- D. CO2
viii) The mass of one molecule of water is:
- A. 18amu
- B. 18 g
- C. 18mg
- D. 18kg
Short Questions Class 9 Fundamentals of Chemistry
Q.1) Define industrial chemistry and analytical chemistry.
Answer:
Industrial chemistry
Industrial chemistry is the branch of chemistry that applies physical and chemical processes for the manufacturing of chemical compounds like ammonia, caustic soda, fertilizers, glass, soap, etc on a commercial scale.
Analytical chemistry
Analytical chemistry is the branch of chemistry that studies the separation, identification, and quantification of the chemical components of natural and artificial materials.
Q.3) Give the scope of biochemistry.
Answer:
Biochemistry deals with the chemical processes taking place in living organisms. It includes the synthesis and metabolism of biomolecules. The various biomolecules are carbohydrates, proteins, lipids, fats, etc. Any imbalance or abnormality in the level of chemical constituents present or chemical transformation taking place in the body leads to a diseased state of the body. Therefore, biochemistry plays an important role in the diagnosis and treatment of diseases.
Q.5) What is the relative atomic mass? How is it related to grammar?
Answer:
The relative atomic mass is the average mass of atoms of an element compared to 1/12th the mass of one atom of the carbon-12 isotope. Its unit is an atomic mass unit, with the symbol amu. One atomic mass unit is 1/12 the mass of one atom of carbon-12.
The atomic mass unit is expressed in grams as follows:
1 amu = 1.66 x 10-24 g
Q.6) Define an empirical formula with an example.
Answer:
Empirical formula
The empirical formula is a chemical formula showing the simplest ratio of elements in a molecule rather than the actual number of atoms of the elements.
Example
Glucose has the molecular formula C6H12O6. The simplest ratio of carbon, hydrogen, and oxygen atoms in this molecule is 1:2:1. Therefore, the empirical formula of glucose is CH2O.
Q.7) State three reasons why you think air is a mixture and water a compound?
Answer:
Air is a mixture because of the following reasons:
i) Air is formed by the simple mixing of nitrogen, oxygen, carbon dioxide, water vapors, etc. And these gasses can be separated by a physical method, fractional distillation.
ii) Proportions of the constituents in air vary from place to place.
iii) The properties of the constituents of air (oxygen, nitrogen, carbon dioxide, etc.) are not changed.
Water is a compound because of the following reasons:
i) Constituents of water cannot be separated by physical methods.
ii) Proportions of the constituents in water are fixed i.e. 11.11% of hydrogen and 88.89% of oxygen by mass are present.
iii) Constituents of water lose their properties and thus water has entirely different properties than that hydrogen and oxygen.
Q.8) Explain why hydrogen and oxygen are considered elements whereas water is a compound.
Answer:
Hydrogen and oxygen are considered elements because they consist of the same type of atoms. Each one of them has the same atomic number and cannot be split up into simpler substances by chemical means.
Water is considered a compound because it is made up of different types of atoms chemically combined in a fixed proportion by mass. The properties of water are entirely different from that of its constituents (hydrogen and oxygen).
Q.9) What is the significance of the symbol of an element?
Answer:
Symbols of one or two letters are used instead of writing the whole name of an element. A symbol represents an atom and the name of an element. It represents a definite mass of the element (equal to atomic mass expressed in grams). It also represents one mole of atoms of the element i.e. it represents 6.022 x 1023 atoms of the element
Q.10) State the reasons: the soft drink is a mixture and water is a compound.
Answer:
Soft drink is a mixture because of the following reasons:
i) Soft drink is made up of simple mixing up of water, sugar, carbonated gasses, flavors, etc.
ii) The properties of the constituents of soft drinks are not changed.
iii) Components of soft drinks can be separated by physical methods.
Water is a compound because of the following reasons:
i) Proportions of the constituents in water are fixed i.e. 11.11% of hydrogen and 88.89% of oxygen by mass are present.
ii) The properties of water are different from that of its constituents (hydrogen and oxygen).
iii) Constituents of water cannot be separated by physical methods.
Q.11) Classify the following into element, compound, or mixture:
i) He and H2
ii) CO and Co
iii) Water and milk
iv) Gold and brass
v) Iron and steel
Answer:
I) He: Element
H2: Compound
ii) CO: Compound
Co: Element
iii) Water: Compound
Milk: Mixture
iv)Gold: Element
Brass: Mixture
v) Iron: Element
Steel: Mixture
Q.12) Define atomic mass unit. Why is it needed?
Answer:
It is a unit of mass used to express atomic and molecular weights, equal to 1/12th of the mass of an atom of carbon-12.
An atomic mass unit is needed because the mass of an atom cannot be determined practically, as it is too small. Hence, a standard was needed concerning which atomic masses of elements could be determined.
Q.19) In which one of the following the number of hydrogen atoms is more? 2 moles of HCl or 1 mole of NH3 (Hint: 1 mole of a substance contains as many moles of atoms as are in 1 molecule of a substance.
Answer:
1 mole of HCl contains = 1 mole of atoms of hydrogen
2 moles of HCl contains = 1 x 2 = 2 mole of atoms of hydrogen
1 mole of NH3 contains = 3 moles of atoms of hydrogen
Hence, the number of hydrogen atoms is more than 1 mole of NH3.
Long Questions Fundamentals of Chemistry cha 1 bise rawalpindi
Q.1) Define elements and classify the elements with examples.
Answer:
Element
Element is a substance that consists of only one type of atom, having the same atomic number that cannot be decomposed into simpler substances by an ordinary chemical process.
Classification of elements
On the basis of their properties, elements are classified into metals, nonmetals, and metalloids.
i) Metals
Metals are good conductors of heat and electricity. They are malleable and ductile and have a shiny surface. About 80% of elements are metals.
Examples:
Sodium, magnesium, potassium, calcium, aluminum, zinc, copper, iron, mercury, etc.
All the metals are solids except mercury, which is liquid at room temperature.
ii) Non-metals
Non-metals are bad conductors of heat and electricity. They are not malleable and ductile and do not have a shiny surface.
Examples:
Hydrogen, carbon, bromine, chlorine, sulfur, nitrogen, etc.
All the non-metals are solids or gasses except bromine, which is liquid at room temperature.
iii) Metalloids
Metalloids have properties of both metals and nonmetals. They are quite a few.
Examples:
Boron, germanium, silicon, etc.
Q.2) List five characteristics by which compounds can be distinguished from mixtures.
Answer:
- A compound is formed by a chemical reaction between the atoms of elements.
- Compounds have properties entirely different from those of its constituents.
- Compounds have fixed composition by mass; therefore, they have a definite formula.
- Compounds have definite melting and boiling points.
- The components of compounds cannot be separated by physical methods.
A mixture lacks all the above-mentioned attributes.
Q.3) Differentiate between the following with examples:
i) Molecule and gram molecule
ii) Atom and gram atom
iii) Molecular mass and molar mass
iv) Chemical formula and gram formula
Answer:
i) Molecule and gram molecule
| Molecule | Gram molecule |
| The molecule is the smallest unit of a compound that can exist independently and shows all the properties of that compound. | The gram molecule is the expression of the molecular mass of a compound in grams. It is also called a mole. |
| Examples:N2 (nitrogen)O2 (ozone) | Examples:1 gram molecule of O2 = 32 g = 1 mol of oxygen1 gram molecule of H2O = 18 g = 1 mol of water |
ii) Atom and gram atom
| Atom | Gram atom |
| Atom is the smallest unit of an element that can or cannot exist independently and shows all the properties of that element. | Gram atom is the expression of the atomic mass of an element in grams. It is also called a mole. |
| Examples: Neon, Nehydrogen, H | Examples:1 gram atom of oxygen = 16 g = 1 mol of oxygen1 gram atom of carbon = 12 g = 1mol of carbon |
iii) Molecular mass and molar mass
| Molecular mass | Molar mass |
| Molecular mass is the mass of a molecule; it is the sum of the masses of its atomic components. The unit for molecular mass is amu. | Molar mass is the mass of 1 mole of a substance. The unit for molar mass is g/mol |
| Example: Molecular mass of H2O = 18 amu | Example:Molar mass of H2O = 18 g/mol |
iv) Chemical formula and gram formula
| Chemical formula | Gram formula |
| The chemical formula is the shorthand notation of a compound. It represents one molecule of a compound and indicates the elements of that compound. | The gram formula is the formula mass of an ionic compound expressed in grams. |
| Example: Chemical formula of carbon dioxide = CO2 | Example:Gram formula of NaCl = 58.4 g |
Q.4) Mole is the SI unit for the amount of a substance. Define it with examples?
Answer:
Mole
Mole is the mass of any chemical substance that contains the same number of chemical units (atoms, molecules or formula units) as there are atoms in exactly 12 grams of carbon-12. This number is expressed by the Avogadro constant, which has a value of 6.02 x 1023. Mole has the unit symbol mol.
Avogadro’s number of particles are present in one molar mass or formula mass of a substance. Therefore, a mole can also be defined as the atomic mass, molecular mass, or formula mass of a substance expressed in grams.
Examples:
Atomic mass of H = 1 g = 1 mol of H
Molecular mass of H2O = 18 g = 1 mol of H2O
Formula mass of NaCl = 58.5 g = 1 mol of NaCl
The concept of the mole helps to put quantitative information about what happens in a chemical equation on a macroscopic level. It is used to express the quantities involved in chemical reactions. For example
2H2 + O2 → 2H2O
The above chemical equation implies that 2 moles of H2 and 1 mole of O2 react to form 2 moles of water (H2O).
Numericals
Question no: 1 Sulphuric acid is the king of chemicals if you need 5 moles of Sulphuric acid for a reaction. How many grams of it will you weigh?
Solution:
Molar mass of H2SO4 = 2 + 32 + 64
Moles of H2SO4= 5
Mass/Weight=?
Formula:
Unknown mass = moles * molar mass
= 5 * 98g
We will weigh 490 g of sulphuric acid to get 5 moles (Answer)
Question no: 2 Calcium Carbonate is insoluble in water. If you have 40g of it how many Ca+2 and Co3-2 ions are present in it?
Solution:
CaCo3 ———–> Ca+2 + Co3-2
1 Molecule of CaCo3 Gives 1 Ca+2 and 1 Co3-2 ions
Given Mass = 40g
Moles =?
Molar mass of CaCo3 = 100g
Formula
Moles = Given Mass/Molar Mass
Moles = 40/100 = 0.4
Number of Ca+2 ions = 1 (moles × NA)
= 1 (0.4 × 6.02 × 1023)
= 2.4 × 1023
Number of Co3-2 ions = 1 (moles × NA)
= 1 (0.4 × 6.02 × 1023)
= 204 × 1023
40g of calcium carbonate has 2.4 × 1023 Ca+2 ions and 2.4 × 1023 Co3-2 ions. (Answer)
Question no: 3 If you have 6.02 × 1023 ions of aluminum how many sulfate ions will be required to prepare Al2(SO4)3.
Solution:
Al2(SO4)3 —————-> 2Al+ + 3SO4-2
1 molecule of Al2(SO4)3 gives 2Al+3 ions and 3SO4-2 ions.
- If we have 1 mole of Al2(SO4)3 then
The number of Al+3 Ions is = 2(6.02 × 1023)
Number of SO4-2 ions are = 3 (6.02 × 1023)
- If we have ½ mole of Al2(SO4)3 then
Number of Al+3 ions are = 1/2 × 2 (6.02 × 1023)
= 6.02 × 1023
The number of SO4-3 ions is = 1/2 × 3 (6.02 × 1023)
= 9.03 × 1023
So if we have 6.02 × 1023 ions of aluminum then 9.03 × 1023 Sulfate ions will be required. (Answer)
Question no: 4 Calculate the number of molecules in
A: 16g of H2CO3
B: 20g of HNO3
C: 30g of C6H12O6.
Solution:
A) 16g of H2CO3
Given mass = 16g
Molar mass = 2+12+48 = 62g
Moles of H2CO3 = ?
Formula:-
Moles = given mass/Molar mass
Putting the value of mass and molar mass in the above formula you get
Moles: 16/62 = 0.26
Several moles =?
Formula:-
Number of moles = Moles × NA
By putting the value
Number of moles = 0.26 × 6.02 × 1023
= 1.56 × 1023
B) 20g of HNO3
Given mass = 20g
Molar mass = 1 + 14 + 48
= 63g
Moles = ?
Formula:- Moles = given mass/ molar mass
By putting the value
Moles = 20/63 = 0.31
Number of moles = ?
Formula: – number of molecules = moles × NA
= 0.31 × 6.02 × 1023
= 1.86 × 1023
C) 30g C2H12O6
Given mass = 30g
Molar mass = 72 + 12 + 96 = 180g
Moles = given mass/molar mass
= 30/180 = 0.76
Number of molecules = moles × NA
= 0.76 × 6.02 × 1023
= 4.57 × 1023
