EmSAT Chemistry 4

Question 1

What is the IUPAC name of the compound CH₃CH₂CH(OH)CH₃?

Accepted Answer

2-butanol

Answer

The hydroxyl group is on carbon 2 of a four-carbon chain, making this butan-2-ol, commonly written as 2-butanol.

Question 2

Which gas is produced when dilute hydrochloric acid reacts with zinc metal?

Accepted Answer

Hydrogen

Answer

Zinc displaces hydrogen from the acid: Zn + 2HCl → ZnCl₂ + H₂, releasing hydrogen gas.

Question 3

The half-life of a radioactive isotope is 10 days. What fraction of the original sample remains after 30 days?

Accepted Answer

1/8

Answer

30 days = 3 half-lives, and (1/2)³ = 1/8 of the original sample remains.

Question 4

Which of the following molecules has a trigonal planar geometry?

Accepted Answer

BF₃

Answer

BF₃ has three bonding pairs and no lone pairs around boron, giving a trigonal planar shape with 120° bond angles.

Question 5

During the electrolysis of aqueous copper(II) sulfate using copper electrodes, what happens at the anode?

Accepted Answer

Copper dissolves into solution

Answer

The copper anode undergoes oxidation (Cu → Cu²⁺ + 2e⁻), dissolving into the solution and replenishing Cu²⁺ ions.

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