SCIENCE 5 REVIEW(1st Quarter)

1. Which of these is undergoing a physical change?

• A.    Melting ice

• B.     Burning wood

• C.   Rusting of iron

• D.    Cooking an egg

Answer explanation

Melting ice is a physical change because it involves a change in the state of matter from solid to liquid. The chemical composition of the ice remains the same during the process of melting.

Which of these exemplifies a physical change?

 

•  

  A.    Ripening fruits

• B.     Cutting paper

• C.   Digesting food

• D.    Burning a candle

Answer explanation

Cutting paper is a physical change because it involves a change in the shape or size of the paper, but the chemical composition of the paper remains the same. The paper is still made of the same material after it has been cut.

Which of the following is/are example/s of a physical change?

 

I.   rusting of iron

II. wood cut into small pieces

III. food digestion

IV. baking soda and vinegar reaction

• A.      I only

• B.      II only

• C.     I, III, and IV

• D.     All of the above

Answer explanation

Wood being cut into small pieces is an example of a physical change because it involves a change in the shape or size of the wood, but the chemical composition of the wood remains the same.

Rusting of iron, food digestion, and the reaction between baking soda and vinegar are examples of chemical changes because they involve a rearrangement of atoms and the formation of new substances with different chemical properties.

Which of the R’s does not belong to the group?

• A. Reduce

• B.  Reheat

• C. Recycle

• D. Reuse

Answer explanation

The other options (Reduce, Recycle, Reuse) are all related to the concept of sustainability and minimizing waste. Reheating, on the other hand, does not fit into this category as it refers to the act of heating something again, which does not necessarily have a direct connection to reducing waste or promoting sustainability.

Global warming is the increase in the Earth’s average temperature.

• TRUE

• FALSE

Answer explanation

Global warming refers to the long-term increase in the Earth's average temperature, primarily due to the buildup of greenhouse gases in the atmosphere. This increase in temperature can have various impacts on the climate and ecosystems worldwide.

Chlorofluorocarbons are chemical compounds made up of atoms of chloride, fluorine, and carbon.

• TRUE

• FALSE

Answer explanation

Chlorofluorocarbons, or CFCs, are synthetic organic compounds that contain chlorine, fluorine, and carbon atoms. They were commonly used in various industries, such as refrigeration, air conditioning, and aerosol propellants. However, it was discovered that CFCs contribute to the depletion of the ozone layer in the Earth's atmosphere. As a result, their production and use have been phased out under the Montreal Protocol to protect the ozone layer.

The bubbles formed by mixing baking soda and vinegar are evidence of a

                                 chemical change.

• TRUE

• FALSE

Answer explanation

When baking soda and vinegar are combined, a chemical reaction occurs. The reaction produces carbon dioxide gas, water, and a salt called sodium acetate. The formation of carbon dioxide gas is responsible for the bubbles that are observed during the reaction. This chemical reaction is commonly used in baking and other household applications.

The boiling point of water at sea level is __________ degrees Celsius.

Answer explanation

_____________________________ point is the temperature at which a substance changes from a liquid

       to a gas.

The phase change from a solid to a liquid occurs when the temperature of a substance reaches its

       ______________________________ point.