CHEMISTRY SCIENCE CLASS 10

Which of the following is a chemical reaction?

• Water freezes.
• Sugar dissolves in water.
• Salt and pepper are mixed in a dish.
• Iron rusts.

Tags

NGSS.MS-PS1-2

Before a chemical reaction, the total mass of two reactants is measured to be 40 grams.  After the reaction, what should be the total mass of the products?

• 0 grams
• 20 grams
• 40 grams
• 80 grams

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

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

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

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

The first part of a balanced chemical equation is shown:  H₂SO₄ + 2NaOH → ________.  In order for this equation to be balanced, how many hydrogen (H) atoms must be present in the products?

• 2
• 3
• 4
• 5

Tags

NGSS.MS-PS1-5

A teacher writes the equation representing the chemical reaction between hydrochloric acid and sodium on the board.HCl + Na → NaCl + H₂The teacher states that the equation has not been balanced. Which of these correctly shows the products of this reaction after the equation has been balanced?

• Na₂Cl + H₂
•  2NaCl + H₂
• NaCl + 2H₂
•  2NaCl + 2H₂

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

The law of conservation of matter states that:

• matter is neither created nor destroyed.
• the mass of the products is always greater than the mass of the reactants.
•  the mass of the products is always less than the mass of the reactants.
• matter is always converted into an equal amount of energy.

Which of the following statements about the given reaction are correct?

3Fe_(s) + 4H₂O_(g) ® Fe₃O_4(s) + 4H_2(g)

(i) Iron metal is getting oxidised

(ii) Water is getting reduced

(iii) Water is acting as reducing agent

(iv) Water is acting as oxidising agent

• (a) (i), (ii) and (iii)

• (b) (iii) and (iv)

• (c) (i), (ii) and (iv)

• (d) (ii) and (iv)

Which of the following are combination reactions?

(i) 2KClO₃ + Heat --> 2KCl + 3O₂

(ii) MgO + H₂O --> Mg(OH)₂

(iii) 4Al + 3O₂ --> 2Al₂O₃

(iv) Zn + FeSO₄ --> ZnSO₄ + Fe

• (a) (i) and (iii)

• (b) (iii) and (iv)

• (c) (ii) and (iv)

• (d) (ii) and (iii)

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