Question Library

Oxyacetylene flames are used for welding iron because they produce a very high temperature that melts the iron. The flame produced by oxyacetylene is very hot, reaching temperatures of around 3,100^\circC. This is hot enough to melt steel, which has a melting point of over 1,500^\circC.

The alkyl group is a type of functional group that has a carbon and hydrogen atom present in its structure. The general formula for an alkyl group is C\(_n\)H\(_{2n+1}\), where n represents a number or integer.

There are three isomers of C\(_5\)H\(_{12}\). They include n-pentane , 2 - methyl butane and 2,2-dimethylpropane.

Substitution reactions are a characteristic reaction of alkanes because they are saturated compounds with only single bonds. This means that hydrogen atoms in an alkane can be easily replaced by other atoms or groups.

Copper(I) chloride does not confirm the presence of a triple bond, rather it is ammoniacal cuprous chloride (Cu(NH\(_3\))\(_2\)ClOH)(CuCl) that can be used to distinguish between double and triple bonds in unsaturated hydrocarbons. The test involves reacting the compound with ammoniacal cuprous chloride to see if a red precipitate forms. If a red precipitate forms, the compound is an alkyne and contains at least one triple bond. If no precipitate forms, the compound is an alkene and contains at least one double bond. To confirm the presence of a triple bond, you can use bromine water (Br₂) or Baeyer's reagent (alkaline potassium permanganate), both of which react with unsaturated bonds (double or triple) by addition reactions, causing the colour of the reagent to disappear.

Vulcanization can cause isomerization of a double bond. This isomerization is a type of stereoisomerism, which is a change in the relative positions of atoms in a molecule. Vulcanization is a process that hardens rubber by forming cross-links between polymer chains.

The decarboxylation reaction of acetic acid (CH\(_3\)COOH) is a process that removes the carboxyl group (−COOH) and replaces it with a hydrogen atom. The reaction produces methane (CH\(_4\)), carbon dioxide (CO\(_2\)).

Dehydration of ethanol is the process of removing water from ethanol to produce ethene, CH\(_2\)=CH\(_2\). This process can be achieved by heating ethanol with concentrated sulphuric acid H\(_2\)SO\(_4\)

The reverse reaction of esterification is hydrolysis. Esterification: A reaction that produces an ester and water when an alcohol and an alkanoic cid react. Hydrolysis: A reaction that produces an alcohol and a carboxylic acid when an ester reacts with water and a strong acid.

Concentrated Sodium chloride solution, or salt, is commonly added to soap solutions to precipitate out the soap as a solid, making it easier to separate and purify. This process is called "salting out" and it relies on the common ion effect. Adding salt increases the ionic strength of the solution, reducing the solubility of the soap and causing it to precipitate out of solution.

Firstly, the longest Carbon chain is a straight chain 6 C atoms ⇒ parent name is hexane Secondly, there are two methyl, CH\(_3\) substituents on C-2 and C-3 ⇒ 2,3 - dimethyl Finally, merge both the substituent as well as the parent name together ⇒ 2,3 - dimethylhexane

Recall that Air is a mixture of gases. These gases comprises mainly nitrogen, oxygen, carbon(IV) oxide, noble gases, and water vapour. From the experiment, the alkaline pyrogallol has already absorbed the oxygen, while the anhydrous calcium chloride being a drying agent has also absorbed the moisture content (water vapour) leaving behind Nitrogen, Carbon(IV) oxide and noble or inert gases.

Firstly, the longest Carbon chain is a straight chain 6 C atoms ⇒ parent name is hexane Secondly, there are two methyl, CH\(_3\) substituents on C-2 and C-3 ⇒ 2,3 - dimethyl Finally, merge both the substituent as well as the parent name together ⇒ 2,3 - dimethylhexane

No expanded working has been attached for this question yet. The verified answer is Option B.

No expanded working has been attached for this question yet. The verified answer is Option C.