Model Test Paper മാതൃകാ ചോദ്യപേപ്പർ
A full paper in the Kerala Class 9 Chemistry pattern, covering the whole of “Organic Chemistry” – sorting formulas into alkanes, alkenes and alkynes, reading and drawing structural formulae, condensed and molecular formulae, IUPAC names from word roots and suffixes, homologous series, ring compounds and benzene, the fractions of petroleum, the forms of coal, natural gas, and greenhouse gases and global warming. Work on paper with a timer before you look at the solutions.
Standard IX · Chemistry
Chapter 8 · കാർബണിക രസതന്ത്രം · Organic Chemistry
- 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.
- In structural formulae show every bond; each carbon atom must have four bonds. Write subscripts clearly (C4H10).
- IUPAC names without position numbers (for example “butene”) are accepted.
SECTION AAnswer all · 8 × 1 = 8 marks
1.
The general formula of the alkynes is
(1)(a) CnH2n+2(b) CnH2n(c) CnH2n−2(d) CnHn
2.
The ability of atoms of an element to join one another in long chains and rings is called .
(1)3.
Find the relation and fill in: C2H6 : ethane :: C2H2 :
(1)4.
Pick the odd one out and give the reason: C2H6, C4H10, C5H10, C7H16
(1)5.
Which of these is an alicyclic compound (ആലിസൈക്ലിക് സംയുക്തങ്ങൾ)?
(1)(a) benzene(b) naphthalene(c) cyclobutane(d) butene
6.
The fraction of petroleum used for tarring roads is
(1)(a) paraffin wax(b) bitumen(c) diesel(d) naphtha
7.
Moth balls (പാറ്റാഗുളിക) are made of the aromatic hydrocarbon .
(1)8.
The Earth’s surface gives out heat as rays; greenhouse gases trap part of them.
(1)SECTION BAnswer all · 5 × 2 = 10 marks
9.
These are open-chain hydrocarbons: C6H10, C8H18, C3H6, C7H14, C4H6, C10H22. Sort them into alkanes, alkenes and alkynes, and write the general formula of each family.
(2)10.
The structural formula of a hydrocarbon is given. (a) Write its condensed formula.
(b) Write its molecular formula.
(c) Write its IUPAC name.
(d) To which family does it belong?
(2)(b) Write its molecular formula.
(c) Write its IUPAC name.
(d) To which family does it belong?
11.
C6H14 and C7H16 are two neighbouring members of a homologous series. (a) What is the difference between their formulas?
(b) Write the molecular formula and the name of the member that comes next.
(c) Write two features of a homologous series.
(2)(b) Write the molecular formula and the name of the member that comes next.
(c) Write two features of a homologous series.
12.
A student drew the structure of propene, C3H6, as shown. (a) Which carbon atom breaks the valency rule, and how many bonds does it have?
(b) Draw the correct structure of propene.
(2)(b) Draw the correct structure of propene.
13.
(a) Why are alkenes and alkynes called unsaturated hydrocarbons?
(b) The alkane family begins with a compound of one carbon atom, but the alkene family begins with a compound of two carbon atoms. Why?
(2)(b) The alkane family begins with a compound of one carbon atom, but the alkene family begins with a compound of two carbon atoms. Why?
SECTION CAnswer all · 4 × 3 = 12 marks
14.
(a) Write the IUPAC names of:
(i) CH3–CH2–CH2–CH2–CH2–CH2–CH3
(ii) CH2=CH–CH2–CH2–CH2–CH2–CH2–CH3
(iii) CH≡C–CH3
(b) Explain how you arrived at the name of (ii).
(c) Without drawing the structures, write the molecular formulas of decane and nonyne.
(3)(i) CH3–CH2–CH2–CH2–CH2–CH2–CH3
(ii) CH2=CH–CH2–CH2–CH2–CH2–CH2–CH3
(iii) CH≡C–CH3
(b) Explain how you arrived at the name of (ii).
(c) Without drawing the structures, write the molecular formulas of decane and nonyne.
15.
P, Q and R are ring compounds.(a) Write the molecular formula of each.
(b) Write the IUPAC names of P and R.
(c) Q and R both have a ring of six carbon atoms. Write two differences between them.
(3)(b) Write the IUPAC names of P and R.
(c) Q and R both have a ring of six carbon atoms. Write two differences between them.
16.
(a) Name the method used to separate the fractions of petroleum. In the tower, where do the fractions with the fewest carbon atoms collect, and why?
(b) Complete the table (from Table 8.9).
(3)(b) Complete the table (from Table 8.9).
| Fraction | Carbon atoms | Use |
|---|---|---|
| gases | C1–C4 | (i) |
| petrol | (ii) | motor fuel |
| (iii) | C10–C16 | domestic fuel |
| paraffin wax | C60–C70 | (iv) |
17.
The bar chart shows the percentage of carbon in four types of coal W, X, Y and Z. (a) Identify W, X, Y and Z.
(b) What is carbonisation?
(c) Coal is a source of aromatic compounds. Name two of them, and give one other use of coal.
(3)(b) What is carbonisation?
(c) Coal is a source of aromatic compounds. Name two of them, and give one other use of coal.
SECTION DAnswer all · 2 × 5 = 10 marks
18.
Read the passage and answer the questions.
(b) Draw the structural formula of methane, the main component of CNG. How many bonds does its carbon atom form?
(c) What do CNG and LNG stand for? How is each obtained from natural gas?
(d) Why is CNG called an eco-friendly fuel?
(e) Methane and butane belong to the same homologous series. Name the members between them, and write the difference between the molecular formulas of methane and butane.
(5)Meera lives in Kochi. Her family cooks on LPG; the main component of the gas in the cylinder is butane. Her uncle drives a CNG autorickshaw, and many city buses also run on CNG. Natural gas reaches Kochi as LNG by ship at the terminal at Puthuvype, and GAIL’s pipeline carries it to factories and to the CNG filling stations. Meera’s teacher says CNG is an eco-friendly fuel.
(a) Write the condensed formula and the molecular formula of butane. Show that it fits the general formula of its family.(b) Draw the structural formula of methane, the main component of CNG. How many bonds does its carbon atom form?
(c) What do CNG and LNG stand for? How is each obtained from natural gas?
(d) Why is CNG called an eco-friendly fuel?
(e) Methane and butane belong to the same homologous series. Name the members between them, and write the difference between the molecular formulas of methane and butane.
19.
Read the passage and answer the questions.
(b) From the table, which gas has the largest share in global warming, and which increases fastest every year?
(c) A student says, “The greenhouse effect is harmful; it should be stopped completely.” Do you agree? Explain.
(d) Write two effects of global warming other than heavy rain.
(e) Suggest two things the eco-club can do to reduce global warming.
(5)In August 2018 Kerala suffered its worst floods since 1924, after days of extremely heavy rain. Scientists say that such extreme rain is becoming more common as the Earth gets warmer. The eco-club of a school in Thrissur studied the table below (Table 8.10) to plan a campaign.
(a) Explain how greenhouse gases keep the Earth warm.| Greenhouse gas | Share in global warming | Increase every year |
|---|---|---|
| carbon dioxide (CO2) | 55 % | 0.5 % |
| methane (CH4) | 15 % | 0.9 % |
| nitrous oxide (N2O) | 6 % | 0.3 % |
| chlorofluorocarbons (CFCs) | 10–24 % | 4 % |
(b) From the table, which gas has the largest share in global warming, and which increases fastest every year?
(c) A student says, “The greenhouse effect is harmful; it should be stopped completely.” Do you agree? Explain.
(d) Write two effects of global warming other than heavy rain.
(e) Suggest two things the eco-club can do to reduce global warming.
*** End of the question paper ***