CSEC Chemistry Paper 2 January 2025 - Free CXC Past Paper with Answers

Students were asked to observe strips of yam placed in a container of distilled water. After 20 minutes, one student suggested that osmosis was occurring in the yam strips.

(i) Define the term 'osmosis'.

Define the term 'osmosis'.

State what the students would have observed after 20 minutes.

Outline how osmosis supports the particulate theory of matter.

The yam strip which was a solid was placed into distilled water that is a liquid. State how the arrangement of particles in a liquid differs from that in a solid.

Account for the observation that the bottles of cold beverages sold at the school canteen often develop drops of water on the sides of the bottles when left to stand.

Table 2 contains information related to the atomic structure of three atoms of the elements X, Y and Z.

TABLE 2: ATOMIC STRUCTURE OF ELEMENTS X, Y AND Z

(i) Complete Table 2 below by inserting the missing information for the atomic structure of each of the atoms of the elements shown.

Complete Table 2 by inserting the missing information for the atomic structure of each of the atoms of the elements shown.

Identify the isotopes in the table above.

Identify the element that is a nonmetal.

State TWO natural sources of hydrocarbons.

Fractional distillation of crude oil produces several fractions that contain a range of compounds with varying numbers of carbon atoms. Three of these fractions, labelled 1, 2 and 3, are shown in Table 3.

TABLE 3: THREE FRACTIONS OF CRUDE OIL

(i) State the name of ONE of the numbered fractions.

State the name of ONE of the numbered fractions.

State ONE use of Fraction 3.

Compound W shown in Figure 3 has the characteristic odour of pears and is used in fragrances and as a food additive.

Figure 3. Compound W

$\qquad \text{H} \quad \text{O}$ $\qquad | \quad // $ $\text{H} - \text{C} - \text{C} - \text{O} - \text{C} - \text{C} - \text{C} - \text{H}$ $\qquad | \quad \quad | \quad | \quad |$ $\qquad \text{H} \quad \quad \text{H} \quad \text{H} \quad \text{H}$

Circle the functional group of Compound W in Figure 3.

Identify the homologous series to which Compound W belongs.

List THREE characteristics of a homologous series.

Draw the FULLY DISPLAYED structural formulae of the two molecules that are produced when Compound W is hydrolysed by dilute hydrochloric acid.

Molecule 1 Molecule 2

State the names of the TWO molecules drawn in (c) (iv).

Molecule 1 Molecule 2

Figure 4 represents an outline of a portion of the periodic table. The position of five unknown elements, L, M, R, Q and T, are shown.

      I   II          III IV V VI VII VIII
    +---+---+       +---+---+---+---+---+---+
    | Na| L |       |   |   |   | Q |   | Ne|
    +---+---+       +---+---+---+---+---+---+
    | K | M |       |   | Si|   | Br| T |
    +---+---+       +---+---+---+---+---+---+
    | R |   |
    +---+---+

Figure 4. Portion of periodic table

State the name of the horizontal rows and vertical columns in the periodic table.

Rows Columns

Outline TWO factors used in arranging the elements in the periodic table.

Based on the position of Element L in the periodic table, state whether it would react more vigorously or less vigorously with dilute hydrochloric acid than Element R.

Justify your response in (b) (i).

Write a balanced chemical equation for the reaction between Element L and hydrochloric acid.

State ONE reaction, other than that with hydrochloric acid that is typical of Element L.

An oxide of Element L is dissolved in water. State the pH range of the solution formed.

Some elements can exist in the solid, liquid or gaseous state at room temperature and pressure, based on their position in the periodic table. Predict the physical state of Element T at room temperature.

Based on the position of Element R, write the formula for its hydrogen carbonate.

The condensed formulae of two organic compounds, A and B, are shown below.

Compound A: $\text{CH}_3\text{CH}_2\text{CHCHCH}_3$ Compound B: ${\text{CH}}_3{\text{CH}}_{}$

Deduce the homologous series to which both Compounds A and B belong.

Write the name of Compound A.

Draw the FULLY DISPLAYED structure for Compound B.

State the name of Compound B.

Compound A displays structural isomerism and one of its isomers is 2-methylbut-2-ene. (i) Define the term 'structural isomers'. (ii) Draw the FULLY DISPLAYED structure of the isomer 2-methylbut-2-ene.

Define the term 'structural isomers'.

Draw the FULLY DISPLAYED structure of the isomer 2-methylbut-2-ene.

State the name of Compound B.

Figure 5 shows the structural formulae for two typical starting materials, Compound C and Compound D, used for making polymers.

Figure 5. Compound C and Compound D

(i) Define the term 'polymer'. (ii) Name the functional group of Compound C and Compound D. (iii) State ONE use of EACH of the following polymers.

Define the term 'polymer'.

Name the functional group of Compound C and Compound D. Compound C Compound D

State ONE use of EACH of the following polymers. Nylon Polypropene

State TWO physical properties of nitrogen gas.

Draw a labelled diagram to show the apparatus used for the laboratory preparation of ammonia gas.

Write a balanced chemical equation for the reaction that takes place in the laboratory preparation of ammonia gas.

Explain why concentrated sulfuric acid, a typical drying agent, CANNOT be used in the preparation of ammonia gas and identify an appropriate alternative drying agent that could be used.

Briefly describe a laboratory test for ammonia gas. Test

Ammonia is used as a raw material in the manufacture of fertilizers such as ammonium nitrate. The excessive use of fertilizers may lead to harmful levels of nitrates in the environment. List THREE harmful effects of excessive nitrates in the environment.