Chemistry Practice Questions Quiz

Chemistry Practice Questions

1. Total Number of Molecules in 10g of Calcium Carbonate:
- The correct answer is (4) 6.02 x 10^22.
- This involves calculating moles of Calcium Carbonate using its molar mass (100g/mol) and then multiplying by Avogadro's number (6.02 x 10^23 molecules/mol).
2. Identifying Atoms, Ions, and Isotopes:
- The correct answer is (3) P, Q, R, S - atoms; T - ion; Q and R - isotopes.
- Atoms have equal protons and electrons.
- Ions have an imbalance between protons and electrons.
- Isotopes of an element have the same number of protons but different numbers of neutrons.
3. Weight of Sodium with Same Number of Atoms as 8g Oxygen:
- The correct answer is (3) 11.5g.
- This requires using the concept of molar mass and the mole concept to determine the mass of sodium with the same number of atoms as 8g of oxygen.
4. Formation of Plaster of Paris:
- The correct answer is (2) CaSO4.1/2H2O.
- Plaster of Paris, CaSO4.1/2H2O, is formed when gypsum, CaSO4.2H2O, is heated.
5. Valency of Ammonium Ion:
- The correct answer is (4) Ammonium ion.
- Potassium, Barium, and Lithium ions have a valency of +1.
- The ammonium ion (NH4+) has a valency of +1.
6. Metal Obtained by Self Reduction Process:
- The correct answer is (4) Ag.
- Self reduction is a process where the metal oxide reacts with itself to form the metal.
- Silver (Ag) is obtained by this process.
7. Bohr's Orbits and Stable Anions:
- The correct answer is (3) 8, 18, 18.
- Bohr's orbits are stationary.
- Electrons in Bohr's orbits have specific energy levels.
- These energy levels are quantized.
- Stable anions have a full outer shell of electrons.
28. Neutral Atom Properties:
- The correct answer is (1) An atom has equal numbers of electrons and protons.
- Neutral atoms have a balance of positive and negative charges.
29. Flowchart for Extraction of Metals:
- The correct answer is (3) Calcination - Roasting - Electrolysis of molten ore - Reduction to metal.
- Calcination is the process of heating ores in the absence of air to drive off volatile compounds and decompose carbonates.
- Roasting is the process of heating ores in air to oxidize sulfides to oxides.
- Electrolysis is used to extract reactive metals from their molten ores.
30. Reactivity of Metals:
- The correct answer is (4) K > Ca > Mg > Zn > Fe > Cu > Ag.
- This represents the reactivity series of metals, where potassium (K) is the most reactive and silver (Ag) is the least reactive.
31. Mixtures and their Properties:
- The correct answer is (3) Cl35 and Cl37 have the same chemical properties.
- Isotopes of the same element have the same number of protons and the same chemical properties.
41. Rusting of Iron Nail:
- The correct answer is (4) C and D.
- Rusting requires both oxygen and water.
- Test tube C and D provide the necessary conditions for rusting.
42. Balancing Chemical Equation:
- The correct answer is (2) 6, 2, 3, 1.
- Balancing chemical equations ensures that the number of atoms of each element is consistent on both sides of the equation.
43. Comparing Atoms and Molecules:
- The correct answer is (3) 28g of N2.
- The number of molecules in 32g of O2 is equal to the number of atoms in 28g of N2.
45. Moles of CO2 After Removing Molecules:
- The correct answer is (2) 1.66 x 10^-3.
- This involves converting the mass of CO2 to moles and then subtracting the number of removed molecules.
46. Symbol of Elements with Same Mass Number:
- The correct answer is (3) Isobars.
- Isobars are atoms of different elements with the same mass number.
47. Increase in Hydrogen Ion Concentration:
- The correct answer is (2) 1000 times.
- Each unit change in pH is a tenfold change in hydrogen ion concentration.
48. Acidic Nature of Dilute Sulphuric Acid:
- The correct answer is (3) (i), (iii), and (iv) only.
- The properties of dilute sulfuric acid listed in (i), (iii), and (iv) confirm its acidic nature.
49. Calcination, Roasting, and Alkali Metals:
- The correct answer is (1) (i) & (iii) only.
- Calcination and roasting are steps in metallurgy.
- Alkali metals are extracted by electrolytic reduction.
50. Brown Precipitate Formation:
- The correct answer is (2) Fe2(SO4)3 & KOH.
- When solutions of Fe2(SO4)3 and KOH are mixed, a brown precipitate of Fe(OH)3 is formed.
51. Isoelectronic Species:
- This question is incomplete.
- An isoelectronic species is a group of ions or atoms that have the same number of electrons.
90. Metal Carbonate Decomposition:
- The correct answer is (3) CaCO3, CaO, CO2.
- When calcium carbonate (CaCO3) is heated, it decomposes into calcium oxide (CaO) and carbon dioxide (CO2).
91. Identifying Elements:
- The correct answer is (3) Be, B, C.
- This involves using the provided hints to deduce the elements based on their properties.
92. Electronic Arrangement and Elements:
- The correct answer is (2) S, O.
- The structure of AB2 suggests sulfur (S) as element A and oxygen (O) as element B.
93. Flow Chart for Extraction of Metals:
- This question is incomplete.
- It requires filling in the blanks in a flowchart related to metal extraction methods.