Month: March 2024

Find the oxidation number of sulphur in Na₂S₂O3.

What is the oxidation number of sulphur in K₂SO₃?

What is the oxidation number of vanadium in V₂O₅?

What is the oxidation state of nitrogen in a nitric acid molecule?

What is the oxidation state of phosphorus in a phosphoric acid molecule?

What is the oxidation number of hydrogen in magnesium hydride, \(\mathrm{MgH}_2\) ?

Which of the underlined element in the following compounds has the highest oxidation number?

Which of the following is true about the oxidation number of the elements in NH₄ClO₃.

What is the oxidation number of \(\mathrm{X}\) in \(\mathrm{XO}_4^{-}\)?

What is the oxidation number of the chromium element in potassium dichromate(VI), \(\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7\) ?

The following ionic equation represents the reaction between acidified potassium dichromate(VI) solution and iron(II) sulphate solution.
\[
\mathrm{Cr}_2 \mathrm{O}_7^{2-}+14 \mathrm{H}^{+}+6 \mathrm{Fe}^{2+} \rightarrow 6 \mathrm{Fe}^{3+}+2 \mathrm{Cr}^{3+}+7 \mathrm{H}_2 \mathrm{O}
\]
What is the change of oxidation number of chromium in the reaction?

The following equation represents the oxidation reaction between ethanol and acidified potassium dichromate(VI).
\[
\begin{aligned}
& 3 \mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}+2 \mathrm{~K}_2 \mathrm{Cr}_2 \mathrm{O}_7+8 \mathrm{H}_2 \mathrm{SO}_4 \rightarrow \\
& \quad 3 \mathrm{CH}_3 \mathrm{COOH}+2 \mathrm{Cr}_2\left(\mathrm{SO}_4\right)_3+2 \mathrm{~K}_2 \mathrm{SO}_4+11 \mathrm{H}_2 \mathrm{O}
\end{aligned}
\]

What is the change in the oxidation number of the element chromium in this reaction?

Diagram 6 shows the chemical formula of a compound.

                       
the IUPAC name and oxidation number of copper element in the compound?

\begin{align}
\begin{array}{|c|l|c|}
\hline & \text { Name of compound } & \begin{array}{l}
\text { Oxidation number of } \\
\text { copper element }
\end{array} \\
\hline \text { A } & \text { Copper(I) oxide } & +1 \\
\hline \text { B } & \text { Copper(I) oxide } & +2 \\
\hline \text { C } & \text { Copper(II) oxide } & +1 \\
\hline \text { D } & \text { Copper(II) oxide } & +2 \\
\hline
\end{array}
\end{align}

The following chemical equation represents the extraction of silicon from quartz using coke.
\[
\mathrm{SiO}_2+\mathrm{C} \longrightarrow \mathrm{Si}+\mathrm{CO}_2
\]
What is the change in oxidation number of silicon?

The following ionic equation shows the reaction between zinc and acid.
\[
\mathrm{Zn}(\mathrm{s})+2 \mathrm{H}^{+}(\mathrm{aq}) \rightarrow \mathrm{Zn}^{2+}(\mathrm{aq})+\mathrm{H}_2(\mathrm{~g})
\]
What is the change in oxidation number of hydrogen?

Which of the following IUPAC names are correct for the respective formulae of substances?

The equation below shows the decomposition of potassium chlorate.

2KClO₃ → 2KCl + 3O₂

Which of the following shows the change of oxidation number of chlorine in the reaction?

The equation represents the redox reaction between ammonia and copper(II) oxide.

2NH₃ + 3CuO → N₂ + 3Cu + 3H₂O

Which of the following is true about the reaction?

The oxidation number of calcium increases when

Which of the underlined substances in the following equations undergo oxidation?

Which of the following statements about a chemical reaction are true?

A substance undergoes oxidation if

Which of the following indicates that a substance undergoes reduction?

Which of the following is NOT true about oxidation and reduction?

Which of the underlined substances in the following equations undergo oxidation?

The half equation represents the reduction reaction of acidified potassium dichromate(VI) solution.
\[
\mathrm{Cr}_2 \mathrm{O}_7^{2-}+\mathrm{xH}^{+}+\mathrm{ye}^{-} \longrightarrow \mathrm{zCr}^{3+}+7 \mathrm{H}_2 \mathrm{O}
\]
What are the value of \(x, y\) and \(z\) ? 

\begin{align}
\begin{array}{|c|c|c|c|}
\hline & x & y & z \\
\hline \text { A } & 14 & 6 & 2 \\
\hline \text { B } & 14 & 5 & 1 \\
\hline \text { C } & 7 & 2 & 1 \\
\hline \text { D } & 7 & 1 & 2 \\
\hline
\end{array}
\end{align}

Reducing agents are ____1____ in a reaction.

Reducing agents cause the other substance in the reaction to ____2____ oxygen.

Which words complete gaps 1 and 2?

Magnesium reacts with copper oxide. The equation for this reaction is shown.

Mg+CuO→MgO+Cu

Which substance is acting as an oxidising agent in this reaction?

Iron is extracted from its oxide using carbon monoxide. The equation is shown.

Fe₂O₃+3CO→2Fe+3CO₂

Which row identifies the reducing agent and explains how it acts as a reducing agent?

Iron can be obtained from iron(III) oxide by heating with aluminium powder. The equation is shown.

2Al+Fe₂O₃→Al₂O₃+2Fe

What is the oxidising agent?

The equation for the reaction of zinc oxide with carbon monoxide is shown.

ZnO+CO→Zn+CO₂

Which statement explains the role of carbon monoxide in this reaction?

Iron oxide reacts with aluminium.

Fe₂O₃+2Al→2Fe+Al₂O₃

Which row identifies the oxidising agent and reducing agent in the reaction?

2 NH₃ + 3CuO → N₂ + 3Cu + 3H₂O

The equation above represents the reaction between ammonia and copper(II) oxide. Which of the following is true about the reaction?

Which of the following equation shows that a chlorine molecule receives 2 electrons to form 2 chloride ions?

Which of the following equation shows that a copper(II) ion receive 2 electrons to form
copper atom?

Which of the following equation shows that a zinc atom donates 2 electrons to form a zinc ion?

The following equation represents the oxidation of magnesium atom.

Mg → Mg²⁺ + 2e-

What is meant by oxidation based on the equation?

Which of the following is a reduction reaction?

Which half equations show that reactant acts as a reducing agent?

I. \(\mathrm{Mg} \longrightarrow \mathrm{Mg}^{2+}+2 \mathrm{e}^{-}\)
II. \(\mathrm{Cu}^{2+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Cu}\)
III. \(2 \mathrm{Cl}^{-} \longrightarrow \mathrm{Cl}_2+2 \mathrm{e}^{-}\)
IV. \(2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{H}_2\)

The reaction between iron(II) sulphate solution and bromine can be represented by the
following equation.

Fe²⁺ + Cl₂ → Fe³⁺ + 2Cl⁻

Which of the following is true about the reaction?

Which of the followings are reducing process?

Which set of definition of oxidation in terms of oxygen, hydrogen and electron is correct?

\[
\begin{array}{|l|l|l|l|}
\hline & \text { Oxygen } & \text { Hydrogen } & \text { Electrons } \\
\hline \text { A } & \text { Gain } & \text { Loss } & \text { Loss } \\
\hline \text { B } & \text { Gain } & \text { Loss } & \text { Gain } \\
\hline \text { C } & \text { Loss } & \text { Gain } & \text { Gain } \\
\hline \text { D } & \text { Loss } & \text { Gain } & \text { Loss } \\
\hline
\end{array}
\]

Find the oxidation number of sulphur in Na₂S₂O3.

What is the oxidation number of sulphur in K₂SO₃?

What is the oxidation number of vanadium in V₂O₅?

What is the oxidation state of nitrogen in a nitric acid molecule?

What is the oxidation state of phosphorus in a phosphoric acid molecule?

What is the oxidation number of hydrogen in magnesium hydride, \(\mathrm{MgH}_2\) ?

Which of the underlined element in the following compounds has the highest oxidation number?

Which of the following is true about the oxidation number of the elements in NH₄ClO₃.

What is the oxidation number of \(\mathrm{X}\) in \(\mathrm{XO}_4^{-}\)?

What is the oxidation number of the chromium element in potassium dichromate(VI), \(\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7\) ?

CHEM0906010
Which of the following statements are true about composite materials?

CHEM0906020
Which of the following are composite material?

CHEM0906030
Which of the followings can be made of composite material?

CHEM0906040
Photochromic glass is used in making

CHEM0906050
Fibreglass is used to make racquets because it is

CHEM0906060
Which of the following material is used in the infrastructures of telecommunication?

Which of the following is not correct about the composite material and its property?