Test on Mixtures, Compounds, and Elements

Question 1: Boiling an egg for a salad is considered a physical change because its atoms have not been rearranged.

A. Ano

B. Ne

Explanation: Boiling an egg for a salad is a chemical reaction because the atoms inside them have been re-arranged.

Question 2: In a mixture, the atoms of the constituent substances are not rearranged.

A. Ano

B. Ne

Explanation: The study materials explain that when substances like iron filings and sulfur powder are stirred together to form a mixture, 'The atoms had not been re-arranged'.

Question 3: According to the study materials, what does the word 'properties' mean in a scientific context?

A. Chemical arrangements

B. Features or characteristics

C. Physical methods

D. Houses or buildings

Explanation: The study materials explicitly state: 'Remember in science, the word properties means features or characteristics, not houses or buildings!'

Question 4: Based on the provided materials, what is a key distinction between a mixture and a substance formed by a chemical reaction?

A. A mixture's atoms are re-arranged and chemically bonded together, while in a substance formed by a chemical reaction, they are not.

B. The components of a mixture retain their individual properties, whereas a substance formed by a chemical reaction results in new properties.

C. Mixtures can only be separated using chemical methods, while substances formed by a chemical reaction can be easily separated using physical methods.

D. Substances in a mixture are chemically joined together, but in a substance formed by a chemical reaction, they are not.

Explanation: The study materials state that when making a salad (a mixture), 'the ingredients mostly keep their individual taste. So, we say their properties have stayed the same.' Similarly, for the iron and sulfur mixture, 'They still had their own individual colour and properties.' Conversely, when iron filings and sulfur powder were heated (a chemical reaction forming a compound), 'The yellow colour disappeared and a dark metal solid was formed, with different properties.'

Question 5: Diatomic elements are defined as atoms that typically exist as single, isolated units.

A. Ano

B. Ne

Explanation: Diatomic elements are characterized by atoms that exist in pairs, such as oxygen and nitrogen. The term itself is derived from the Greek word for 'two' or 'double'.