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The mass of one steel screw is 4.11g. Find the mass of one mole of these steel screws. Compare this value with the mass of the Earth (5.98 × 10²⁴kg). Which one of the two is heavier and by how many times?

Answer: Mass of one steel screw = 4.11g Mass of Earth = 5.98 × 1024 kg = 5.98 × 1027 g 1 mole = 6.022 x 1023 One mole of screws... View Article

Cinnabar (HgS) is a prominent ore of mercury. How many grams of mercury are present in 225 g of pure HgS? Molar mass of Hg and S are 200.6 g mol^-1 and 32 g mol^-1 respectively.

Answer: Molar mass of HgS = The molar mass of Hg + the molar mass of S The molar mass of Hg = 200.6 The molar mass of S = 32 Molar mass of HgS =... View Article

The difference in the mass of 100 moles each of sodium atoms and sodium ions is 5.48002 g. Compute the mass of an electron.

Answer: 9.1×10-31 kg Sodium atom and ion differ by one electron. For 100 moles each of sodium atoms and ions there would be a difference of... View Article

Calcium chloride when dissolved in water dissociates into its ions according to the following equation. CaCl₂ (aq) → Ca₂ + (aq) + 2Cl^– (aq) Calculate the number of ions obtained from CaCl₂ when 222 g of it is dissolved in water.

Answer: 3.6132 × 1024 ions 1 mole of calcium chloride (CaCl2) = 111g ∴ 222g of CaCl2 is equivalent to 2 moles of CaCl2 Since 1... View Article

Find the ratio by mass of the combining elements in the following compounds. (You may use Appendix-III) (a) C₂ H₅ OH (b) NH₃ (c) Ca(OH)₂

Answer: The total sum of the masses of the atoms or elements present in the molecule is termed as molecular mass. Atomic mass of C = 12 Atomic... View Article

Find the ratio by mass of the combining elements in the following compounds. (You may use Appendix-III) (a) CaCO₃ (d) C₂ H₅ OH (b) MgCl₂ (e) NH₃ (c) H₂ SO₄ (f) Ca(OH)₂

Answer: The total sum of the masses of the atoms or elements present in the molecule is termed as molecular mass. Atomic mass of Ca = 40... View Article

Verify by calculating that 240 g of calcium and 240 g magnesium elements have a mole ratio of 3:5.

Answer: Relative molar mass is defined as the smallest mass unit of a compound with one twelfth of the mass of one carbon-12 atom. The units of... View Article

Verify by calculating that (a) 5 moles of CO₂ and 5 moles of H₂ O do not have the same mass.

Answer: Relative molar mass is defined as the smallest mass unit of a compound with one twelfth of the mass of one carbon-12 atom. The units of... View Article

Calculate the number of moles of magnesium present in a magnesium ribbon weighing 12 g. Molar atomic mass of magnesium is 24 g mol^-1.

Answer: A mole is defined as the mass of the substance which consists of the equal quantity of basic units. A mole fraction indicates the number... View Article

You are provided with a fine white coloured powder which is either sugar or salt. How would you identify it without tasting? To examine if the fine white coloured powder is sugar pr salt we can conduct two experiments.

Answer: Sugar melts to liquid form when heated because sucrose has a decomposition and melting point between 190 and 192 degrees Celsius.... View Article

Classify each of the following on the basis of their atomicity. (a) F₂ (b) NO₂ (c) N₂O (d) C₂H₆ (e) P₄ (f) H₂O₂ (g) P₄O₁₀ (H) O₃ (i) HCl (j) CH₄ (k) He (l) Ag

Answer: Atomicity can be defined as the total number of atoms that composes a molecule. Simply put, it is the no of atoms present in a... View Article

Does the solubility of a substance change with temperature? Explain with the help of an example.

Answer: Solubility is the ability of a solute to get dissolved in 100g solvent. Solubility of a given solute to dissolve in specific solvent... View Article

What is the fraction of the mass of water due to neutrons?

Answer: 0.4444 Mass of one mole of a substance is equal to its relative atomic or molecular mass in grams. Mass of one mole of neutrons = 1g Mass... View Article

State the number of atoms present in each of the following chemical species (a) CO₃^-2 (b) PO₄^-3 (c) P₂O₅ (d) CO

Answer: The number of atoms in CO32- = Atom of carbon + Atom of oxygen Atom of carbon = 1 Atom of oxygen = 3 The number of atoms in CO32- = 1... View Article

Give the chemical formulae for the following compounds and compute the ratio by mass of the combining elements in each one of them. (You may use appendix-III). (a) Ammonia (b) Carbon monoxide (c) Hydrogen chloride (d) Aluminium fluoride (e) Magnesium sulphide

Answer: S. No. Compounds Chemical formula Ratio by mass of the combining elements (a) Ammonia NH3 N:H = 14:3 (b) Carbon monoxide CO... View Article

Which of the following symbols of elements are incorrect? Give their correct symbols (a) Cobalt CO (b) Carbon c (c) Aluminium AL (d) Helium He (e) Sodium So

Answer: The Periodic table generally displays only the symbol of the element and not its entire name. Most of the symbols are similar to the name... View Article

Give the formulae of the compounds formed from the following sets of elements (a) Calcium and fluorine (b) Hydrogen and sulphur (c) Nitrogen and hydrogen (d) Carbon and chlorine (e) Sodium and oxygen (f) Carbon and oxygen

Answer: Calcium Fluoride (CaF2) Hydrogen Sulphide (H2S) Ammonia (NH3) Carbon Tetrachloride (CCl4) Sodium Oxide (Na2O)... View Article

Write the cations and anions present (if any) in the following compounds (a) CH₃COONa b) NaCl (c) H₂ (d) NH₄NO₃

Answer: An anion may be defined as an atom or molecule that is negatively charged. A cation may be defined as an atom or molecule that is... View Article

Write the molecular formulae of all the compounds that can be formed by the combination of following ions Cu²⁺, Na⁺, Fe³⁺, Cl^– SO₄^-2, PO₄^-3

Answer: The molecular formula is the expression of the number of atoms of each element in one molecule of a compound. The molecular formula... View Article

Write the molecular formulae for the following compounds (a) Copper (II) bromide (b) Aluminium (III) nitrate (c) Calcium (II) phosphate (d) Iron (III) sulphide (e) Mercury (II) chloride (f) Magnesium (II) acetate

Answer: The molecular formula is the expression of the number of atoms of each element in one molecule of a compound. The molecular formula... View Article