NSO 7th grade test

In an experiment demonstrating oxygen evolution in Hydrilla, sodium bicarbonate is added to water in the experimental set-up. What would happen if all other conditions are favorable?

• Amount of oxygen evolved decreases as carbon dioxide in waste is absorbed by sodium bicarbonate

• Amount of oxygen evolved decreases as the availability of carbon dioxide increases

• Amount of oxygen evolved increases as the availability of carbon dioxide increases

• Amount of oxygen evolved increases as carbol dioxide in water is absorbed by sodium bicarbonate

Which of the following statements is incorrect?

• The process of unwinding the silk filaments from the cocoon and combining them together to make thread of raw silk is called bailing

• Silk fabrics have a good moisture absorbing capacity

• Merino is an exotic breed of sheep

• Woollen fibres obtained from the hair present on the body of the wool-yielding animals trap a lot of air

When you heat a system, its temperature

• Always increases

• Sometimes decreases

• May stay the same

• Always goes up or down, depending on the heat

Which of the following processes represents a neutralisation reaction?

• Applying vinegar on wasp sting

• Brushing our teeth with toothpaste

• Reaction of sodium hydroxide with hydrochloric acid to form sodium chloride

• All of the above

Rishab was performing an experiment with a blue coloured solution (X) in a breaker. By mistake a shaving blade fell into the beaker. After half an hour, he found that the colour of the solution in the beaker changed to green (Y). What could be the solutions to X and Y respectively?

• Copper sulphate, Iron sulphate

• Iron sulphate, Copper sulphate

• Iron sulphate, Zinc sulphate

• Copper sulphate, Zinc sulphate

Read the given statements and select the incorrect one

• The sun rays become more and more slanting as the latitude increases

• Slanting rays spread over a large surface area than vertical rays

• Sun rays fall vertically near the equator

• None of these

The energy required to form and sustain a cyclone is provided by

• Kinetic energy of blowing wind

• Fast moving waves in the sea

• Vaporisation of water

• Condensation of water vapor

Water is inexhausitable, renewable resource, still there is shortage of water at many places of the world. It is because -

• A major part of the water that is present on Earth is not in the usable form

• 97.4% of all available water is frozen in glaciers and polar ice caps

• We cannot make use of water that is present in rivers and lakes

• We cannot make use of rainwater

Select the correct statement

• Phloem tubes are only found in the leaves of plants as this is where the sugars are made

• Anaemia occurs when there are insufficient number of WBCs

• Blood contains many more white blood cells that red blood cells

• None of these

Read the given passage:
The flowers of plant X contain either stamen or pistil while flowers of plant Y contain both stamens and as well as pistils. Select the correct statement regarding plants X and Y

• In X, seed setting is assured even in the absence of pollinating agent

• X could be mustard while Y could be papaya

• In normal conditions, all the flowers of Y will give rise to seeds after fertilisation

• The flowers of X cross pollination