Physical and chemical changes

Which of the following is a combination reaction?

• A + B --------> AB

• AB --------> A + B

• AC +B --------> C + AB

A reaction in which a insoluble solid is formed at the bottom.

(a)  

Is the following reaction exothermic or endothermic

2C + 4S -------->2CS₂

• Endothermic

• Exothermic

• Both

• None

What is the brown powdery substance formed on iron articles? (Give only one word answer and no two word answer)

(a)  

Complete the equation

2Mg + O₂ --------> _______________

• MgO

• 2MgO

• MgO₂

• Mg₂O₂

Balance the equation

N_{2 +} H₂ --------> NH₃

• 2N_{2 +} H₂ --------> 2NH₃

• N_{2 +} 3H₂ --------> 2NH₃

• N_{2 +} 2H₂ --------> 4NH₃

• 2N_{2 +} 2H₂ --------> 3NH₃

When iron nail is dipped in copper sulphate solution, the blue colour of copper sulphate changes to green due to formation of -

(a)  

True or false

Crystallisation is a chemical process

• True

• False

The substance which gets oxidised in a redox reaction is called (a)  

A reaction in which heat is evolved is

• Endothermic Reaction

• Decomposition Reaction

• Exothermic Reaction

• Thermal Reaction