Science class 10

A cell's control center that directs all of the activities that take place in the cell is the

• Chromosome
• Vacuole
• Nucleus
• Mitochondria

Which of the following are exothermic processes? (i) Reaction of water with quick lime (ii) Dilution of an acid(iii) Evaporation of water (iv) Sublimation of camphor (crystals)

• (i) and (ii)
• (ii) and (iii)
• (i) and (iv)
• (iii) and (iv)

Which among the following is(are) double displacement reaction(s)?(i) Pb + CuCl2 → PbCl2 + Cu (ii) Na2SO4 + BaCl2 → BaSO4 + 2NaCl (iii) C + O2 → CO2 (iv) CH4 + 2O2 → CO2 + 2H2O

• (i) and (iv)
• (ii) only
• (i) and (ii)
• (iii) and (iv)

Barium chloride on reacting with ammonium sulphate forms barium sulphate and ammonium chloride. Which of the following correctly represents the type of the reaction involved?(i) Displacement reaction (ii) Precipitation reaction (iii) Combination reaction (iv) Double displacement reaction

• (a) (i) only
• (b) (ii) only
• (c) (iv) only
• (d) (ii) and (iv)

Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is

• (a) 1:1
• (b) 2:1
• (c) 4:1
• (d) 1:2

In the double displacement reaction between aqueous potassium iodide and aqueous lead nitrate, a yellow precipitate of lead iodide is formed. While performing the activity if lead nitrate is not available, which of the following can be used in place of lead nitrate?

• (a) Lead sulphate (insoluble)
• (b) Lead acetate
• (c) Ammonium nitrate
• (d) Potassium sulphate

Copper chloride and aluminum react to produce aluminum chloride and copper.  Which of the following is the correctly balanced chemical equation for this reaction?

• CuCl₂ + Al -> AlCl₃ + Cu
• 3CuCl₂ + Al -> AlCl₃ + 2Cu
• 3CuCl₂ + 2Al -> 2AlCl₃ + 3Cu
• CuCl₂ + 3Al -> AlCl₃ + 2Cu

Which observation would most likely indicate that an exothermic reaction has occurred?

• a color change
• the production of gas bubbles
• an increase in temperature
• a decrease in temperature

When I want to balance a chemical equation, this is the only number that I can change.

• Subscript

• Coefficient

• Elemental Symbol

• Yields

CaO + H₂O --> Ca(OH)₂

This is an example of

• Combination reaction

• Decomposition reaction

• Displacement reaction

• None of the above