Science Practice Quiz 170

Q1.The rusting of iron, where it acquires a film of brownish substance, is presented in the text as an example of what kind of change?

A. Physical change B. Biological change C. Chemical change D. Environmental change

Q2.When a piece of iron is left in the open for some time, it acquires a film of brownish substance. What is this substance called?

A. Oxide B. Corrosion C. Rust D. Patina

Q3.In Activity 5.5, after heating a hack-saw blade and observing its colour change, what happens to its colour after removing it from the flame?

A. It remains permanently changed. B. It gets back its original colour. C. It changes to a different colour. D. It only changes back if dipped in water.

Q4.What is observed when a magnesium ribbon is completely burnt in the atmosphere?

A. It melts into a liquid substance. B. It turns into a black, brittle solid. C. It burns with a brilliant white light and leaves behind a powdery ash. D. It evaporates completely without leaving any residue.

Q5.What is the chemical name of the powdery ash formed when a magnesium ribbon is completely burnt?

A. Magnesium carbonate B. Magnesium hydroxide C. Magnesium oxide D. Magnesium sulfate

Q6.Which of the following statements about rust is correct according to the provided text?

A. Rust is a form of pure iron. B. Rust is chemically identical to the iron it forms on. C. Rust is a new substance, different from the iron on which it gets deposited. D. Rust is formed only when iron is heated to high temperatures.

Q7.When magnesium oxide (ash) is mixed with water, what new substance is formed?

A. Magnesium carbonate B. Magnesium chloride C. Magnesium hydroxide D. Magnesium sulfate

Q8.Based on the information provided, how is magnesium hydroxide classified?

A. As an acid B. As a base C. As a salt D. As a neutral substance

Q9.What safety precaution is mentioned regarding observing a burning magnesium ribbon?

A. It should be observed from a very close distance. B. It is dangerous to look for long at the burning magnesium ribbon. C. It should only be observed in a completely dark room. D. It requires protective eyewear for short glances only.

Q10.Which of the following is a new substance formed on burning of magnesium?

A. Magnesium carbonate B. Magnesium hydroxide C. Magnesium oxide D. Magnesium chloride

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Science Practice Quiz 170