Science Grade 8

Which among the following is a physical change?

• Burning of wood

• Cutting a log of wood in small pieces

• Cooking of food

• Ripening of fruit

Which is a method to prevent rust?

• Galvanization

• Digestion

• Sedimentation

• 
  Crystallization

How are crystal of pure substances obtained?

• By chromatography

• By peptization

• By crystallization

• By none of these

Galvanisation is a process used to prevent the rusting of which of the following?

• Iron

• Zinc

• Aluminium

• Copper

What are the evidences that indicate that a chemical change has taken place? There could be more than one answers.

• color change

• formation of a precipitate

• odor change

• none of these

Pure substances may be divided into two classes:

• minerals and compounds

• elements and minerals

• elements and friction

• elements and compounds

What are elements in regard to pure substance?

• Pure substances that cannot be broken down into simpler substances by physical changes

• Pure substances that cannot be broken down into simpler substances by chemical changes

• None of these

• Pure substances that are comprised of two or more elements.

What are compounds in regard to pure substances?

• Pure substances that are comprised of two or more elements

• Pure substances that cannot be broken down into simpler substances by chemical changes

• Pure substances that cannot be broken down into simpler substances by physical changes

• None of these

Which of the following best describes a chemical mixture?

• 1. When two substances are combined but are not chemically bonded

• 1. A compound made from different elements

• 1. None of the Above

• 1. A substance made through chemical bonding

Which of the following is NOT a property of a mixture?

• 1. The proportion of the components is variable

• 1. The original properties of the combined substances are changed

• 1. The components can be easily separated

• 1. Two or more substances are combined