basic concepts of chemistry, Law of chemical combination, Atomic and molecular masses, Mole concept, Stoichiometry.
The basic concepts of chemistry and fundamental principle of chemistry, such as the Law of Chemical Combinations which governs the ratios for combining elements to form compounds, is examined in Nokryan.com. Understanding atomic and molecular mass is crucial; atomic mass is the mass of an atom, whereas molecular mass is the mass of a molecule. In order to understand these basic concepts, nokryan.com is a valuable resource,
1. The following statement contained in a student’s laboratory report is a conclusion
- Colour of the gas is greenish yellow
- A gas is liberated
- The gas is chlorine
correct - Oxide of the gas is strongly acidic
2. Empirical formula and formula unit of an ionic compound:
- Ionic compounds do not have any empirical formula
- Are always different
- May be similar or different
correct - Are always similar
3. What is the correct relationship between empirical and molecular formulas?
- Molecular Formula/n= Empirical formulacorrect
- Empirical formula /n=Molecular formula
- Empirical formula x n²=Molecular formula
- Empirical formula x√n=Molecular formula
4. Isotopes differ in the
- Number of protons
- Number of neutrons
correct - Number of electrons
- Number of atoms
5. A molecule ion is formed by
- Passing high energy electron beam through gaseous moleculecorrect
- Dissolving a salt in dilute acid
- Passing electricity through aqueous solutions
- Passing electric current through molten salt
6. Which of the following is not related to a.m.u?
- gm/litcorrect
- gram
- Kilogram
- microgram
7. The relative atomic mass of chlorine is 35.5. What is the mass of 2 moles of chlorine gas?
- 35.5g
- 71g
correct - 142g
- 18.75g
8. All of the following statements are incorrect for 20 mol of hydrogen
- 30 mol of hydrogen atoms
- 20 mol of hydrogen atoms
- 30 mol of oxygen atoms
- 80 mol of atoms
correct
9. Who determined atomic masses of elements?
- J. Berzelius
correct - Aston
- Dempster
- Avogadro
10. A pharmacist prepared 50 ml sample of a cough mixture. It was found that it has a mass of 46g. What is the density (g/ml) of this mixture? Stated to correct number of significant figures?
- 1.04
- 1.087
- 0.90
- 0.92
correct
11. A piece of paper is burnt in air, the gas produced is passed through distilled water. The pH of water will be
- 6.8
correct - 7
- 2.1
- 3
12. An atom is:
- Smallest indivisible particle is an element
- Smallest particle of an element which can undergo a chemical reaction
correct - Always smaller than molecule
- Building block of an element
13. Mass spectrometer measures the
- Exact mass of an element
- m/e values of a positive ion
correct - average mass of an element
- The number of elements present is a molecule
14. Which of the following statements is not true?
- Isotopes with even atomic masses and odd atomic numbers are comparatively abundant
- Isotopes of add atomic masses are comparatively abundant
- Isotopes with even atomic masses are comparatively abundant
- Isotopes with even atomic masses and even atomic numbers are comparatively abundantcorrect
15. The mass of 2 moles of sodium hydroxide will be
- 80g
correct - 40g
- 20g
- 2g
16. Isotopes differ in:
- Properties which depend upon
correct - The extent to which they may be affected in election magnetic field
- Arrangement of electrons in orbitals
- Chemical properties
17. Which of the following produced in the ionization of mass spectrometer?
- F₂⁺, O₂⁺, H₂⁺
- F¯,O¯²,H¯
- F₂, O₂, H₂
- F⁺, H⁺, O⁺
correct
18. The number of moles of CO₂ which contain 8g of Oxygen?
- 1.0
- 1.50
- 0.25
correct - 0.05
19. Which of the following statements is correct for a chemical reaction?
- Collide with energy more than energy of activationcorrect
- Collide with each other
- Collide with high frequency
- Collide with energy less than energy of activation
20. “A” compound always consists of the same elements combined in the same fixed ratio. “The statement is”
- A fact
- A lawcorrect
- An observation
- A hypothesis
Entry Test 2021 Chemistry Basic Concepts MCQS Online Preparation Sample Paper 2 Questions with Answer
1. The soul of chemistry is its dealing with
- Composition and properties of matter
correct - Properties of matter
- Composition of matter
- Internal structure changes in matter
2. Which is the correct statement about limiting reactant?
- It is left behind after the completion of reaction
- It gives least number of moles of productcorrect
- It is most a cheaper substance as compared to other reactants
- It gives greatest number of moles of products
3. A vessel contains 10g of N₂, 10g of H₂ and 10g O₂. Which one has the largest number of atoms?
- All have equal number of atoms
- O₂
- H₂correct
- N₂
4. One mole of SO₂ contains.
- 4.2g of atoms of SO₂
- 18.1 x 10²³ molecules of SO₂
- 6.02 x 10²³ atoms of sulphurcorrect
- 3.02 x 10²³ atoms of oxygen
5. A compound having the highest % age of oxygen by weight is?
- C₂H₅OH
- HCOOH
- CH₃ – OH
- H₂Ocorrect
6. The relative abundance of the ion with a definite m/e value is measured by:
- High pressure of vapours
- Quantity of fast moving electrons
correct - Electron gas
- Strength of electric current measured
7. The volume occupied by 1.4g of N₂ at S.T.P is
- 1.12 dm³
correct - 112 cm³
- 2.24 dm³
- 22.4 dm³
8. Many elements have fractional atomic masses. The reason is that
- Atomic masses are average masses of isotopes
- Atomic masses are average masses of isotopes which are proportional to their relative abundance
correct - The mass of atom is itself fractional
- Atomic masses are average masses of isobars
9. Copper (II) oxide is mixed with organic compound during combustion. The purpose is:
- All of above
- To carry out complete combustion
correct - To reduce the time for completion of the reaction
- To reduce the economy of the process
10. A ring contains 1.2g of diamond. How many number of carbon atoms re in diamond?
- 6.02 x 10²³
- 3.01 x 10²²
- 6.02 x 10²²correct
- 3.01 x 10²³
11. One cm³H₂ gas at S.T.P. contains number of atoms
- 1 x 10²⁰
- 0.53 x 10²⁰correct
- 1.67 x 10²⁴
- 6 x 10²³
12. 27g of Al reacts completely with how much mass of O₂ to produce Al₂O₃?
- 8g of oxygen
- 24 g of oxygencorrect
- 16 g of oxygen
- 32 g of oxygen
13. Freezing point of a substance is a temperature of which a liquid substance is converted to solid. It is
- Exactly the same as its melting point
- Always lower than its melting point
- None of these
correct - Usually a little lower than its melting point
14. The mass of one mole of electron
- 0.104 mg
- 1.673mg
- 0.55 mg
correct - 1.008 mg
15. When energy is released during a reaction, it is
- A bond breaking reaction
- Exothermic reaction
correct - A free radical reaction
- Endothermic reaction
16. The empirical formula of the compound having 50% sulphur and 50% oxygen by mass is
- SO₃
- SO
- S₂O₃
- SO₂
correct
17. The reaction? 4NH₃ + 3O₂ → 2N₂ + 6H₂O indicates that?
- One mole of NH₃ will produce 6 moles of N₂
- For the complete reaction of 2 mole of NH₃ 40g of O₂ are required
- One mole of NH₃ will produce 1/2 moles of N₂
correct - For the complete reaction of 2 mole of NH₃ 20g of O₂ are required
18. A limiting reactant is the one which
- Carries the maximum amount of product which is required
- Gives the minimum amount of the product under consideration
correct - Is taken in lesser quantity in grams as compared to other reactants
- Is taken in lesser quantity in volume as compared to other
19. Which set of species has the same number of electrons?
Ca⁺⁺, Mg⁺⁺, A1⁺⁺- F¯, Na⁺, Ne⁰
correct - F¯, C1¯, Br¯
- O⁺, O¯, O⁰
20. A compound has molar mass = 228.3g/mol. When it was analyzed by a scientist, It was found that it contains 30.68% nitrogen. How many nitrogen atoms are there in each molecule of dye?
- 3
- 4
- 5
correct - 6
Entry Test 2021 Chemistry Basic Concepts MCQS Online Preparation Sample Paper 3 Questions with Answer
1. When the following reaction equations is properly balanced number of moles of O₂ will be: C₃H₈ + O₂ → CO₂ + H₂O
- 3 moles
- 5 molescorrect
- 3.5 moles
- 1.5 moles
2. The identity of an element is determined by
- The number of its protons
- The number of its neutrons
- The number of its electrons
- Its atomic masscorrect
3. The number of molecules in 10Cm³ of chlorine gas at S.T.P. is
- 1.003 x 10²³
- 2.7 x 10²⁰
correct - 2.7 x 10 ²²
- 1.003 x 10²²
4. Tin has isotopes
- 11
correct - 3
- 9
- 6
5. Point out the element having atomic mass = 63.546
- Ni
- Br
- Zn
- Cu
correct
6. What are the ratios among the volumes of gases of ³²O₂, ²H₂ and ¹⁶CH₄, if they taken in equal masses?
- 1 : 1 : 1
- 2 : 16 : 2
- 1 : 16 : 2
correct - 2 : 16 : 1
7. Which of the following contains 3.01 x 10²² silver ions?
- 18.5g AgNO₃
- 8.5AgNO₃
correct - 0.85g Ag NO₃
- 0.085g AgNO₃
8. Choose the exact name of formula which is based on the actual molecule?
- Simple formula
- Empirical formula
- Structural formula
- Molecular formula
correct
9. What are the number of water molecules in 9g of water
- 3.01 x 10²⁴
- 6.02 x 10²³correct
- 3.01 x 10²³
6.02 x 10²²
10. What will be the pressure of vapours as these are sent to the ionization chamber?
- 10¯⁷ to 10¯⁸ torr
- 10¯⁵ to 10¯⁶ torr
- 10¯⁶ to 10¯⁷ torr
correct - 10¯³ to 1¯⁴ torr
11. The compound having highest % age of oxygen is
- CH3COCH₃
- CH₃COOH
- C₂H₅OH
- H₂O
correct
12. One mole of (NH₄)₂ HPO₄ contains ______ moles of hydrogen atoms.
- 9
correct - 6
- 5
- 1
13. Gold has isotopes
- 3
- 1correct
- 4
2
Chemistry
- Basic Concepts
- Experimental Techniques
- Gases
- Liquids and Solids
- Atomic Structure
- Chemical Bonding
- Alcohols, Phenols And Ethers
- Solutions
- Chemical Equilibrium
- Electro Chemistry
- Periodic Classification Of Elements & Periodicity
- The Halogens and Noble Gases
- Group III A And IV A Elements
- S-Block Elements
- Fundamental Principles of Organic Chemistry