Kuiz Sains Tambahan Tingkatan 5 Bab 4 Set 1

SELAMAT DATANG Kuiz Sains Tambahan Tingkatan 5 Bab 4 Set 1

Tenaga Dan Perubahan Kimia (English)

KUIZ INI MENGANDUNGI 10 SOALAN

In a simple chemical cell constructed with magnesium and copper electrodes in an electrolyte, why does the magnesium strip become thinner over time?

Copper ions from the solution deposit onto the magnesium strip.

The magnesium strip physically flakes off due to the electric current.

Magnesium atoms lose electrons to become magnesium ions.

Electrons from the copper strip react with the magnesium.

None

What is the primary function of adding cryolite (Na3AlF6) to aluminium oxide (Al2O3) during the industrial extraction of aluminium?

To act as a catalyst and speed up the reaction.

To significantly lower the melting point of aluminium oxide.

To increase the purity of the final aluminium product.

To prevent the carbon anodes from oxidizing.

None

During the electrolysis of molten lead(II) bromide (PbBr2), which products are formed at the anode and cathode respectively?

Lead(II) ions at the anode and bromide ions at the cathode.

Lead metal at the anode and bromine gas at the cathode.

Bromine gas at the anode and lead metal at the cathode.

Hydrogen gas at the cathode and oxygen gas at the anode.

None

In a photochromic lens, what causes the glass to darken upon exposure to sunlight?

The glass undergoes a permanent chemical change

A heat-sensitive dye embedded in the glass changes color

Silver halide crystals decompose into dark silver particles.

The glass absorbs light and then releases it as heat.

None

Why are photosensitive chemicals such as silver bromide and hydrogen peroxide typically stored in dark or opaque bottles?

To prevent chemical reactions with the glass container.

To protect them from decomposition caused by light.

To prevent them from evaporating quickly.

To keep the chemicals at a constant cool temperature.

None

What is the specific process that uses light energy to split water molecules into hydrogen ions and oxygen during photosynthesis?

Photosynthesis

Electrolysis

Hydrolysis

Photolysis

None

A chemical reaction has a change in enthalpy value of ΔH=−1204 kJ mol−1. Which statement accurately describes this reaction?

The reaction is endothermic, absorbing heat from the surroundings.

The products have a higher energy content than the reactants.

The surroundings would feel colder as the reaction proceeds.

The reaction is exothermic, releasing heat into the surroundings.

None

Which of the following reaction equations represents an endothermic process?

Zn+2HCl→ZnCl2 +H2 ΔH = −152 kJ mol−1

C+2S→CS 2 ΔH=+320 kJ mol−1

C2H5OH + 3O2 →2CO2 + 3H2O ΔH = −1270 kJ mol−1

2Mg + O2 →2MgO ΔH = −1204 kJ mol−1

None

What happens to the electrons at the positive terminal (cathode) of a simple chemical cell, such as one made of zinc and copper?

They flow from the cathode to the anode through the external wire.

They combine with the atoms of the cathode material.

They are released by the copper electrode into the solution.

They are accepted by positive ions from the electrolyte.

None

10.

When electroplating an iron spoon with copper, which of the following setups is correct?

The iron spoon is the cathode, and the electrolyte is copper(II) sulfate.

The electrolyte is a solution of iron(II) sulfate.

The iron spoon is the anode, and a copper bar is the cathode.

Both the anode and cathode are made of iron.

None

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