Exam practice

sodium chloride

Baking soda

sugarcane

sodium
(sugar is the word left over.)

Chemicals used for cleaning are called cleansers. They remove dirt, grease and stains, and some kill germs.

When it is heated, or mixed with something sour, baking soda gives off carbon dioxide gas. Bubbles of the gas are trapped in the dough, so it rises and becomes soft and spongy.

• Common salt: gives food a salty taste and preserves pickles.
• Sugar: sweetens tea and food, and preserves jam.

(Baking soda, oil, ghee or vinegar, with their uses, are also right.)

Viruses stick to our hands when we touch things, and enter our body when we touch our eyes, nose or mouth. Soap breaks open the outer fatty layer of many viruses, such as the coronavirus, and lifts them off the skin so that water washes them away. A sanitizer (with alcohol) kills germs on hands when soap and water aren’t at hand. So washing and sanitizing hands stops the viruses before they get into our body.

• Wear rubber gloves and boots, and open the window or door for fresh air.
• Scrub the stains with a brush and a toilet cleaner or detergent.
• Wash the floor and pan with phenol (phenyl) mixed with water, to kill germs, remove the smell and keep flies away.
• Rinse well with plenty of water.
• Never mix two cleaners together, since some mixtures give off poisonous gas.
• Clean the toilet every day, and keep a bucket of water there for flushing.

Soap and water can’t dissolve this ink. Use a stain remover: put a little on the stain, rub gently, leave it for a few minutes, then wash the cloth with detergent and rinse it. (A little rubbing alcohol, such as hand sanitizer, also loosens ballpoint ink.) Treat the stain soon, before it dries in.

• a.Sugar sweetens food and drinks and preserves jam. Baking soda makes bread and cakes rise, and is a medicine for acidity. Salt gives food a salty taste and preserves pickles, fish and meat.
• b.Too much sugar causes tooth decay and too much weight (obesity), and can lead to diabetes. Too much baking soda causes bloating, vomiting and diarrhea. Too much salt raises blood pressure, which can lead to heart and kidney diseases.

transfer (pass on, or conduct)

metal (metals)

Iron
(mineral is the word left over.)

A metal is a substance that is usually hard and shiny, can be beaten into sheets and drawn into wires, conducts heat and electricity, and rings when struck. Examples: iron, copper, gold.

Three properties:

1. Metals have luster (they shine).
2. Metals are malleable: they can be beaten into sheets.
3. Metals are good conductors of heat and electricity.

1. Hammer it on a hard stone. A solid non-metal breaks or crumbles into pieces; a metal flattens.
2. Put it across the gap in a circuit with a cell and a bulb. With a non-metal, the bulb stays dark; with a metal, it lights.

(Other tests: a non-metal makes a dull sound when tapped, and has no shine.)

1. Metals are good conductors of heat, so the heat of the fire passes quickly to the food.
2. Metals are malleable, so they can be beaten and pressed into the shape of pots and pans. (They are also strong, and have high melting points, so they don’t melt in the fire.)

Non-metals are substances that don’t have the properties of metals: they are usually soft and dull, don’t ring when struck, are neither malleable nor ductile, and are bad conductors of heat and electricity. Examples: oxygen and sulphur (also carbon, nitrogen and hydrogen).

• Iron: rods for buildings; nails, tools and pots. (Also: steel, sheets and wires.)
• Copper: electric wires; gagri and other utensils. (Also: coins, idols, brass.)
• Gold: jewelry; coins and medals. (Also: tooth crowns, parts of phones.)

• Too much soap, detergent and phenol pollutes soil and water. Detergents break down slowly, spoil the soil, harm plants and kill fish.
• Metal waste such as blades, nails and cans doesn’t rot; it litters the land and can injure people and animals.
• Poisonous metals such as lead and mercury, from batteries and thermometers, harm water animals and people.
• Burning coal, diesel and petrol and making cement fill the air with smoke and carbon dioxide.

Rubbish often found: wrappers of noodles, biscuits and sweets; plastic bottles and bags; juice boxes; paper; leftover food; pen refills.

Suggestions:

1. Keep separate bins for paper, plastic, metal and food waste, and label them.
2. Ask students to bring tiffin in boxes and water in reusable bottles, not plastic wrappers.
3. Stop selling packed junk food in the canteen.
4. Make compost from food waste and leaves for the school garden.
5. Sell paper, bottles and metal to a kawadi for recycling.
6. Run a cleaning campaign each week, with a class in charge.

Lead is a poisonous metal. When petrol with lead is burnt in engines, the lead comes out with the smoke as tiny particles. People breathe them in, and they settle on soil, water and crops. Lead harms the brain and nerves, most of all in children (it slows their learning and growth), and it damages the kidneys and blood. So environmentalists object. For this reason, leaded petrol was banned for cars all over the world; the last country stopped selling it in 2021.

Plan four paragraphs: 1. Your village and what makes it beautiful. 2. Where rubbish comes from (packets, plastic, waste from shops and houses, careless dumping). 3. Its harm (bad smell, flies and mosquitoes, disease, blocked drains, dirty streams, harm to animals). 4. Solutions (sorting waste, compost, recycling, less plastic, cleaning campaigns, rules about dumping) and what you will do.

Our village is a beautiful place

Our village lies on a green hillside, with terraced fields, a stream and tall trees. In the morning the birds sing, and on a clear day we can see the white mountains. People here help each other, and we are proud of our village.

But our village is not as clean as it should be. Plastic bags, noodle wrappers and bottles lie beside the road and in the stream. Shops throw their waste behind their buildings, and some people dump rubbish on the riverbank. Plastic doesn’t rot, so it piles up year after year.

This rubbish causes many problems. It smells bad and attracts flies, rats and mosquitoes, which spread diseases such as diarrhea and dengue. Plastic blocks the drains, so water floods the road in the monsoon. Cattle that eat plastic bags fall ill, and the stream that once had fish is now dirty.

We can solve these problems together. Every house can sort its waste: food and leaves into a compost pit, and paper, bottles and metal for the kawadi. We can carry cloth bags to the shop and refuse plastic ones. The ward office can place bins and fine those who dump rubbish. Our school can hold a cleaning day each month. If each of us does a little, our village will be not only beautiful, but clean and healthy too.