About this quiz
Soap, detergent, plastic, fibre, glass, fertiliser and pesticide.
This Lok Sewa practice set has 52 multiple-choice questions (Subject: General Science · For: Nayab Subba, Kharidar, Section Officer · Level: Medium). Take the quiz above first; after that, use the study list below to revise every question with its correct answer and a short explanation.
Study list: all 52 questions with answers and explanations
Soap is made by heating fats or oils with:
- A) An alkali ✔
- B) An acid
- C) Sand
- D) Salt water only
Why: Soap is made by heating fats or oils with an alkali such as sodium hydroxide. The fat breaks down and forms soap (a salt of fatty acids) plus glycerol.
The chemical reaction that makes soap is called:
- A) Saponification ✔
- B) Fermentation
- C) Polymerisation
- D) Oxidation
Why: Saponification is the reaction of fats or oils with an alkali to form soap and glycerol. The word comes from Latin 'sapo', soap.
Which by-product is obtained while making soap?
- A) Glycerol ✔
- B) Ethanol
- C) Ammonia
- D) Urea
Why: Glycerol (glycerine) is formed along with soap. It is used in cosmetics, medicines and explosives.
Hard soap is made using:
- A) Sodium hydroxide ✔
- B) Potassium hydroxide
- C) Hydrochloric acid
- D) Calcium carbonate
Why: Sodium hydroxide (caustic soda, NaOH) gives hard soap, such as bathing and washing bars.
Soft (liquid) soap is made using:
- A) Potassium hydroxide ✔
- B) Sodium hydroxide
- C) Sulphuric acid
- D) Silica
Why: Potassium hydroxide (caustic potash, KOH) gives soft or liquid soap, such as shaving soap and liquid hand wash.
The part of a soap molecule that attaches to oil and dirt is the:
- A) Hydrophobic tail ✔
- B) Hydrophilic head
- C) Nucleus
- D) Glycerol
Why: A soap molecule has a hydrophobic (oil-loving) tail that grips oil and dirt and a hydrophilic (water-loving) head facing water. They form micelles that rinse away.
Soap does not lather well in:
- A) Hard water ✔
- B) Soft water
- C) Rain water
- D) Distilled water
Why: In hard water, calcium and magnesium ions react with soap to form insoluble scum, so soap is wasted and gives little lather.
Hard water contains salts of:
- A) Calcium and magnesium ✔
- B) Sodium and potassium
- C) Gold and silver
- D) Nitrogen
Why: Hard water contains dissolved salts of calcium and magnesium (bicarbonates, chlorides, sulphates). Boiling removes temporary hardness.
Which cleaning agent works well in hard water?
- A) Detergent ✔
- B) Ordinary soap
- C) Glycerol
- D) Lime
Why: Detergents work well in hard water because their calcium and magnesium salts dissolve and don't form scum.
Phosphates from detergents in lakes cause:
- A) Eutrophication (excess algae) ✔
- B) Ozone depletion
- C) Acid rain only
- D) Earthquakes
Why: Phosphates act as nutrients, so algae grow fast (eutrophication). When the algae die and rot, oxygen falls and fish die.
Plastics are:
- A) Polymers ✔
- B) Single atoms
- C) Metals
- D) Minerals
Why: Plastics are polymers: very long chain molecules made by joining many small units (monomers), mostly from petroleum.
The small units that join to form a polymer are:
- A) Monomers ✔
- B) Isotopes
- C) Ions
- D) Cells
Why: Monomers are the small units that link together to form a polymer. Example: ethylene monomers join to form polyethylene.
A plastic that softens on heating and can be reshaped is:
- A) Thermoplastic ✔
- B) Thermosetting
- C) Ceramic
- D) Glass
Why: A thermoplastic softens when heated and can be reshaped many times, for example polythene and PVC, so it can be recycled.
Which is a thermosetting plastic?
- A) Bakelite ✔
- B) Polythene
- C) PVC
- D) PET
Why: Bakelite is a thermosetting plastic: once set by heat it stays hard and does not soften again.
Electrical switches are usually made of:
- A) Bakelite ✔
- B) Polythene
- C) Nylon
- D) Rayon
Why: Bakelite is used for switches and plugs because it is a good electrical insulator and does not soften with heat.
Melamine is used for making:
- A) Crockery (plates) ✔
- B) Water pipes
- C) Bags
- D) Ropes
Why: Melamine is a heat-resistant thermosetting plastic used for crockery such as plates and cups, which do not break easily.
PVC is commonly used for:
- A) Pipes and cables ✔
- B) Cooking pans
- C) Window glass
- D) Silk
Why: PVC (polyvinyl chloride) is used for water pipes, cable insulation and raincoats because it is strong and waterproof.
Non-stick pans are coated with:
- A) Teflon ✔
- B) Bakelite
- C) Nylon
- D) Rayon
Why: Non-stick pans are coated with Teflon (PTFE), which is slippery and heat-resistant, so food does not stick.
The first fully synthetic plastic was:
- A) Bakelite ✔
- B) Polythene
- C) Nylon
- D) PVC
Why: Bakelite, made by Leo Baekeland in 1907, was the first fully synthetic plastic.
A major problem of plastics is that they are:
- A) Non-biodegradable ✔
- B) Too heavy
- C) Edible
- D) Magnetic
Why: Most plastics are non-biodegradable: microbes cannot break them down, so they stay in soil and water for hundreds of years.
Burning plastic releases:
- A) Toxic gases like dioxins ✔
- B) Pure oxygen
- C) Only water vapour
- D) Nothing
Why: Burning plastic releases toxic gases such as dioxins and furans, which harm the lungs and can cause cancer.
The 3R principle stands for:
- A) Reduce, reuse, recycle ✔
- B) Read, write, repeat
- C) Rain, river, road
- D) Run, rest, relax
Why: The 3Rs are Reduce, Reuse, Recycle: use less, use things again, and turn waste into new products.
Cotton is a:
- A) Natural plant fibre ✔
- B) Animal fibre
- C) Synthetic fibre
- D) Mineral fibre
Why: Cotton is a natural plant fibre from the seed hairs of the cotton plant. It absorbs sweat, so it is comfortable in summer.
Silk is obtained from:
- A) Silkworm cocoons ✔
- B) Sheep
- C) Cotton plant
- D) Petroleum
Why: Silk is an animal fibre from the cocoons of silkworms. Rearing silkworms is called sericulture.
Pashmina comes from:
- A) Mountain goats ✔
- B) Silkworms
- C) Jute
- D) Petroleum
Why: Pashmina is the fine, soft under-wool of mountain goats (Chyangra) of the high Himalaya, and Nepal is famous for it.
Allo fibre comes from:
- A) Himalayan nettle ✔
- B) Sheep
- C) Petroleum
- D) Bamboo only
Why: Allo is fibre from the Himalayan giant nettle (सिस्नो / allo). It is woven into bags and cloth in Nepal's hills.
Rayon is called:
- A) Artificial silk ✔
- B) Natural wool
- C) Glass fibre
- D) Steel
Why: Rayon is called artificial silk. It is a semi-synthetic fibre made from cellulose (wood pulp).
The first fully synthetic fibre was:
- A) Nylon ✔
- B) Rayon
- C) Cotton
- D) Jute
Why: Nylon, made by Wallace Carothers in 1935, was the first fully synthetic fibre. It is strong and used for ropes and stockings.
Polyester is also called:
- A) Terylene ✔
- B) Rayon
- C) Jute
- D) Allo
Why: Terylene is a common polyester fibre. It is wrinkle-resistant and often blended with cotton.
Why are synthetic clothes risky in fire?
- A) They melt and stick to the skin ✔
- B) They are fireproof
- C) They turn into water
- D) They glow
Why: Synthetic fibres such as nylon and polyester melt when they burn and stick to the skin, causing severe burns. Cotton is safer in kitchens.
Jute is mainly used for:
- A) Sacks and ropes ✔
- B) Window glass
- C) Pipes
- D) Fuel
Why: Jute is a strong, cheap plant fibre used for sacks, ropes and mats. It grows in the eastern Terai.
Glass is mainly made from:
- A) Silica (sand), soda ash and limestone ✔
- B) Iron and copper
- C) Clay and water only
- D) Plastic
Why: Glass is made by melting silica (sand) with soda ash (sodium carbonate) and limestone (calcium carbonate).
Glass is an example of:
- A) Amorphous solid ✔
- B) Crystalline metal
- C) Gas
- D) Polymer
Why: Glass is an amorphous solid: its particles have no regular crystal pattern, so it is sometimes called a supercooled liquid.
Heat-resistant laboratory glass is:
- A) Borosilicate (Pyrex) glass ✔
- B) Soda-lime glass
- C) Lead glass
- D) Coloured glass
Why: Borosilicate (Pyrex) glass contains boron oxide, so it expands little and does not crack with sudden heating or cooling.
Common window glass is:
- A) Soda-lime glass ✔
- B) Pyrex
- C) Crystal glass
- D) Fibre glass only
Why: Soda-lime glass, made from sand, soda and lime, is the most common and cheapest type, used for windows and bottles.
Blue colour in glass comes from:
- A) Cobalt oxide ✔
- B) Chromium oxide
- C) Iron filings
- D) Salt
Why: Cobalt oxide gives glass a blue colour.
Green colour in glass can come from:
- A) Chromium oxide ✔
- B) Cobalt oxide
- C) Gold
- D) Sulphur
Why: Chromium oxide (and iron oxides) give glass a green colour, as in some bottles.
Decorative sparkling glass is:
- A) Lead (crystal) glass ✔
- B) Soda-lime glass
- C) Pyrex
- D) Safety glass
Why: Lead (crystal) glass contains lead oxide, which bends light strongly and makes it sparkle. It is used for decorative glassware.
NPK stands for:
- A) Nitrogen, phosphorus, potassium ✔
- B) Nickel, platinum, krypton
- C) Neon, potassium, carbon
- D) Nitrogen, protein, calcium
Why: NPK stands for nitrogen, phosphorus and potassium, the three main nutrients plants need from fertilisers.
Urea mainly supplies:
- A) Nitrogen ✔
- B) Potassium
- C) Phosphorus only
- D) Calcium
Why: Urea mainly supplies nitrogen, which helps leafy growth. It is the most used chemical fertiliser in Nepal.
Urea contains about how much nitrogen?
- A) 46% ✔
- B) 10%
- C) 80%
- D) 5%
Why: Urea, CO(NH₂)₂, contains about 46% nitrogen, the highest of common solid fertilisers.
DAP mainly supplies:
- A) Phosphorus (and nitrogen) ✔
- B) Only potassium
- C) Only calcium
- D) Carbon
Why: DAP (diammonium phosphate) mainly supplies phosphorus, plus some nitrogen. Phosphorus helps roots and flowering.
Potash (MOP) supplies:
- A) Potassium ✔
- B) Nitrogen
- C) Phosphorus
- D) Sulphur
Why: Muriate of potash (MOP, potassium chloride) supplies potassium, which strengthens plants and improves grain and fruit quality.
Rhizobium bacteria act as:
- A) Bio-fertiliser fixing nitrogen ✔
- B) Pesticide
- C) Plastic
- D) Detergent
Why: Rhizobium bacteria live in root nodules of legumes (beans, peas, lentils) and fix nitrogen from air, so they act as a natural bio-fertiliser.
Overuse of chemical fertilisers can make soil:
- A) Acidic and less fertile over time ✔
- B) More fertile forever
- C) Magnetic
- D) Radioactive
Why: Too much chemical fertiliser, without organic manure, makes soil acidic, harms soil life and lowers fertility over time.
A herbicide is used to kill:
- A) Weeds ✔
- B) Insects
- C) Fungi
- D) Rats
Why: A herbicide kills unwanted plants (weeds), which compete with crops for water and nutrients.
A fungicide controls:
- A) Fungi such as blight ✔
- B) Weeds
- C) Rats
- D) Birds
Why: A fungicide controls fungal diseases such as late blight of potato and rust in wheat.
A rodenticide kills:
- A) Rats and mice ✔
- B) Insects
- C) Weeds
- D) Fungi
Why: A rodenticide kills rodents such as rats and mice, which damage stored grain.
DDT was banned mainly because of:
- A) Persistence and biomagnification in food chains ✔
- B) Low cost
- C) Bad smell only
- D) Colour
Why: DDT stays in the environment for a long time and builds up in animals up the food chain (biomagnification), harming birds and people.
Increasing concentration of a chemical up the food chain is:
- A) Biomagnification ✔
- B) Saponification
- C) Polymerisation
- D) Fermentation
Why: Biomagnification is when a chemical becomes more concentrated at each level of the food chain, so top predators get the highest doses.
IPM stands for:
- A) Integrated Pest Management ✔
- B) International Plastic Market
- C) Indian Pesticide Mission
- D) Insect Production Method
Why: IPM means Integrated Pest Management: combining crop rotation, natural enemies, traps and only limited pesticide use, for safer pest control.
Neem-based products are examples of:
- A) Bio-pesticides ✔
- B) Synthetic plastics
- C) Glass
- D) Detergents
Why: Neem-based products are bio-pesticides: natural pest killers made from plants that break down quickly and are safer than chemical pesticides.