Model Test Paper മാതൃകാ ചോദ്യപേപ്പർ
A full paper in the Kerala Class 9 Chemistry pattern, covering the whole of “Solutions” – solute, solvent and the types of solutions, like dissolves like, mass percentage (forward and reverse), saturated, unsaturated and supersaturated solutions, reading a solubility table and curve, gases with temperature and pressure, true solutions, suspensions and colloids with the Tyndall effect, the types of colloids and food additives. Work on paper with a timer before you look at the solutions.
Standard IX · Chemistry
Chapter 6 · ലായനികൾ · Solutions
- The first 15 minutes are cool-off time: read every question and plan your answers; do not write.
- Answer all questions. Marks for each question are shown on the right.
- Show the formula and every step in calculations, with units (g, %, °C). Take 1 mL of water as 1 g.
- Solubility means grams of solute that saturate 100 g of the solvent at the stated temperature.
SECTION AAnswer all · 8 × 1 = 8 marks
1.
Which of the following is a solid solution?
(1)(a) soda water(b) air(c) brass(d) tincture of iodine
2.
A solution in which the maximum amount of solute has dissolved at a given temperature is called a solution.
(1)3.
Find the relation and fill in: sugar solution : true solution :: muddy water :
(1)4.
The size of the particles in a colloid is
(1)(a) 0.01 nm – 1 nm(b) 1 nm – 1000 nm(c) more than 1000 nm(d) less than 0.01 nm
5.
The scattering of a beam of light by colloidal particles, which makes the path of the light visible, is called the .
(1)6.
Which of these will make more carbon dioxide dissolve in water?
(1)(a) warming the water(b) increasing the pressure(c) decreasing the pressure(d) leaving the bottle open
7.
The solubility of potassium nitrate in water at 20 °C is 32 g. This means
(1)(a) 32 g of potassium nitrate dissolves in 100 g of solution(b) 32 g of potassium nitrate is needed to saturate 100 g of water at 20 °C(c) 32 g of potassium nitrate dissolves in 100 g of water at any temperature(d) the saturated solution at 20 °C is a 32 % solution
8.
Tartrazine is added to soft drinks to give them a colour.
(1)SECTION BAnswer all · 5 × 2 = 10 marks
9.
12 g of sugar is dissolved in 68 g of water. (a) What is the mass of the solution?
(b) Find the mass percentage of sugar in the solution.
(2)(b) Find the mass percentage of sugar in the solution.
10.
To make kalkandam (sugar candy), Ammini’s grandfather dissolves as much sugar as he can in hot water and lets the syrup cool slowly without disturbing it. The cool syrup holds more sugar than water at room temperature can normally dissolve. (a) What is such a solution called?
(b) He hangs a thread with a few small sugar crystals into the syrup. After some days big crystals form on the thread. Why? Name the process.
(2)(b) He hangs a thread with a few small sugar crystals into the syrup. After some days big crystals form on the thread. Why? Name the process.
11.
At a petty shop a bottle of soda is opened with a “pop” and it fizzes. A bottle left open in the afternoon sun goes flat much faster than one kept cold. (a) Which factor is used in the factory to dissolve a large amount of carbon dioxide in soda water?
(b) Explain why the soda fizzes when it is opened, and why the warm one goes flat faster.
(2)(b) Explain why the soda fizzes when it is opened, and why the warm one goes flat faster.
12.
Complete the table.
(2)| Solution | Solute | Solvent | State of the solution |
|---|---|---|---|
| (a) bronze (88 % copper, 12 % tin) | |||
| (b) vinegar (about 5 % acetic acid in water) |
13.
For each colloid, write the dispersed phase and the dispersion medium, and name the type of colloid: (a) mist in the high ranges of Idukki
(b) soap lather.
(2)(b) soap lather.
SECTION CAnswer all · 4 × 3 = 12 marks
14.
(a) How much salt and how much water are needed to make 400 g of a 5 % salt solution?
(b) A bottle contains 500 g of bleaching solution with 3.62 % sodium hypochlorite (NaOCl). What mass of NaOCl is in it?
(c) How much water must be added to 30 g of sugar to make a 12 % sugar solution?
(3)(b) A bottle contains 500 g of bleaching solution with 3.62 % sodium hypochlorite (NaOCl). What mass of NaOCl is in it?
(c) How much water must be added to 30 g of sugar to make a 12 % sugar solution?
15.
The table and the graph give the solubility of three salts in g per 100 g of water.
(a) Whose solubility changes the least with temperature, and whose the most?
(b) How much potassium chloride is needed to saturate 200 g of water at 30 °C?
(c) A saturated solution of potassium nitrate in 100 g of water at 70 °C is cooled to 30 °C. What mass of crystals separates? Name the process.
(3)| Temperature (°C) | 0 | 30 | 50 | 70 |
|---|---|---|---|---|
| Potassium nitrate (KNO3) | 13 | 46 | 85 | 138 |
| Potassium chloride (KCl) | 28 | 37 | 43 | 48 |
| Sodium chloride (NaCl) | 36 | 36 | 37 | 38 |
(b) How much potassium chloride is needed to saturate 200 g of water at 30 °C?
(c) A saturated solution of potassium nitrate in 100 g of water at 70 °C is cooled to 30 °C. What mass of crystals separates? Name the process.
16.
The solubility of potassium chloride at 30 °C is 37 g. Three beakers each have 100 g of water at 30 °C. In P, 25 g of potassium chloride is dissolved; in Q, 37 g; in R, 42 g (R was made at 50 °C and cooled carefully; it is clear). (a) Name the kind of solution in P, Q and R.
(b) A small crystal of potassium chloride is dropped into each beaker. What will you see in each?
(c) How much more potassium chloride can P dissolve at the same temperature?
(3)(b) A small crystal of potassium chloride is dropped into each beaker. What will you see in each?
(c) How much more potassium chloride can P dissolve at the same temperature?
17.
Give the scientific reason. (a) On hot summer afternoons fish in a temple pond come up to the surface and gulp air.
(b) A mechanic first rubs a little kerosene on his greasy hands before washing them with soap and water.
(c) On a misty night on the Thamarassery ghat road the beams of the headlights are clearly seen, but on a clear night they are not.
(3)(b) A mechanic first rubs a little kerosene on his greasy hands before washing them with soap and water.
(c) On a misty night on the Thamarassery ghat road the beams of the headlights are clearly seen, but on a clear night they are not.
SECTION DAnswer all · 2 × 5 = 10 marks
18.
Read the passage and answer the questions.
(b) Find the mass percentage of sugar in Shameer’s syrup.
(c) For a less sweet drink he mixes 100 g of the syrup with 500 g of water. What is the mass percentage of sugar now?
(d) Why are a stabiliser and a preservative added to the bottled drink?
(e) The sarbath must be drunk soon after it is made, but the bottled drink lasts for months. Which is the better choice for health? Give one reason.
(5)Shameer runs a juice shop near Kozhikode beach. For one glass of kulukki sarbath he puts into a tall shaker: crushed ice, a spoonful of soaked basil seeds (kasakasa), a pinch of salt, the juice of half a lime with the lime pieces dropped in, a slit green chilli and some sugar syrup. He tops it up with cold soda water, covers the shaker with a glass and shakes it hard. He makes the sugar syrup every morning by dissolving 600 g of sugar in 400 g of hot water. On his shelf there are also bottles of a lemon-flavoured soft drink. Its label reads: Ingredients: carbonated water, sugar, lemon flavour, stabiliser (glyceryl ester of rosin), preservative (sodium benzoate), colour (tartrazine). Best before 6 months from packing.
(a) Name two substances in the sarbath that dissolve in water and two that do not.(b) Find the mass percentage of sugar in Shameer’s syrup.
(c) For a less sweet drink he mixes 100 g of the syrup with 500 g of water. What is the mass percentage of sugar now?
(d) Why are a stabiliser and a preservative added to the bottled drink?
(e) The sarbath must be drunk soon after it is made, but the bottled drink lasts for months. Which is the better choice for health? Give one reason.
19.
Study the experiment and answer the questions.
(b) The beakers are left undisturbed for an hour and then the contents are filtered. In which beaker do the particles settle, and in which is a residue left on the filter paper?
(c) Classify A, B and C as true solution, colloid or suspension, and give the range of particle size of each.
(d) Neither A nor B settles. Why is the beam seen in B and not in A?
(e) Beaker A is replaced by a clear solution of sodium thiosulphate to which 2–3 drops of dilute hydrochloric acid are added. What will you see in the beam over the next few minutes? Why?
(5)In a dark room a torch is shone from the side through three glass beakers kept in a row: A – copper sulphate dissolved in water (clear blue); B – water with a few drops of milk stirred in; C – water with chalk powder stirred in.
(a) In which beakers is the path of the light seen? What is this effect called?(b) The beakers are left undisturbed for an hour and then the contents are filtered. In which beaker do the particles settle, and in which is a residue left on the filter paper?
(c) Classify A, B and C as true solution, colloid or suspension, and give the range of particle size of each.
(d) Neither A nor B settles. Why is the beam seen in B and not in A?
(e) Beaker A is replaced by a clear solution of sodium thiosulphate to which 2–3 drops of dilute hydrochloric acid are added. What will you see in the beam over the next few minutes? Why?
*** End of the question paper ***