Chemistry · Karatasi 2 · 2008
37 maswali 🇹🇿 NECTA ✓ Majibu rasmi ya NECTAChemistry · Karatasi 2 · 2008
37 maswali
Mtihani wa saa 3 wa muda · husahihishwa kiotomatiki · huhesabiwa kwenye nafasi
Lipa na anza mtihani →Sehemu A
The gas used in balloons is:
Match each item in List A with a correct response in List B by writing its letter below the number of the corresponding item in the table provided. LIST A (i) Gas that produces a pop sound (ii) Coating iron with paint (iii) Separates solids from liquids (iv) Element with atomic number 16 (v) Forms blue solution with copper(II) sulphate (vi) Apparatus for precise liquid dispensing (vii) Liquid used in batteries (viii) Method to obtain sugar from solution (ix) Gas used in fire extinguishers (x) Element in group I, period 3 LIST B A. Oxygen B. Rust prevention C. Filtration D. Sulphur E. Water F. Pipette G. Sulphuric acid H. Evaporation I. Carbon dioxide J. Sodium
Boresha ili kuona majibu ya mfano.
Sehemu B
(a) Define the term "molecule". (b) Name three types of chemical bonds. (c) Give one example of a compound formed by each bond type in (b).
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(a) What is meant by the term "covalent bond"? (b) Draw diagrams to show the electron arrangement in: (i) A nitrogen atom (atomic number 7) (ii) A nitrogen molecule (N₂) (c) State the type of bond formed between hydrogen and oxygen in water.
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(a) Define the term "suspension". (b) List three properties of a suspension. (c) Name one method to separate mud from muddy water.
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(a) What is meant by the term "extinguisher"? ............................................................................................................................................................. ............................................................................................................................................................. (b) Name three types of fire extinguishers. ............................................................................................................................................................. ............................................................................................................................................................. (c) State one precaution when using a water extinguisher. ............................................................................................................................................................. .............................................................................................................................................................
Boresha ili kuona majibu ya mfano.
(a) Define the term "isotope". ............................................................................................................................................................. ............................................................................................................................................................. (b) Calculate the number of neutrons in: (i) Carbon-12 (atomic number 6) (ii) Carbon-14 (atomic number 6) ............................................................................................................................................................. ............................................................................................................................................................. (c) State one use of isotopes in science. ............................................................................................................................................................. .............................................................................................................................................................
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(a) What is meant by the term "hazard symbol"? ............................................................................................................................................................. ............................................................................................................................................................. (b) List three hazard symbols found in a chemistry laboratory. ............................................................................................................................................................. ............................................................................................................................................................. (c) State the meaning of one symbol listed in (b). 5
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(a) Define the term "hydrogen". ............................................................................................................................................................. ............................................................................................................................................................. (b) Describe a laboratory test for hydrogen gas. ............................................................................................................................................................. ............................................................................................................................................................. (c) Name one industrial use of hydrogen. ............................................................................................................................................................. .............................................................................................................................................................
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(a) What is meant by the term "water hardness"? ............................................................................................................................................................. ............................................................................................................................................................. (b) Name two types of water hardness. ............................................................................................................................................................. ............................................................................................................................................................. (c) State one method to remove temporary hardness from water. ............................................................................................................................................................. ............................................................................................................................................................. ............................................................................................................................................................. ............................................................................................................................................................. ............................................................................................................................................................. ............................................................................................................................................................. 6
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