The pH of water is:
The pH of pure water is 7. In general, water with a pH lower than 7 is considered acidic, and with a pH greater than 7 is considered basic. The normal range for pH in surface water systems is 6.5 to 8.5, and the pH range for groundwater systems is between 6 to 8.5.
Plants regulate their temperature by:
Plants regulate the rate of transpiration by controlling the size of the stomatal apertures. The rate of transpiration is also influenced by the evaporative demand of the atmosphere surrounding the leaf such as boundary layer conductance, humidity, temperature, wind and incident sunlight.
The rate of photosynthesis is very high during
During daylight, photosynthesis is the dominant process as a result amount of O 2 O_2 O2 released during day time is ten times greater than the amount of O 2 O_2 O2 utilized in day time. Because, respiration is more dominant in night time than day time
Read the following information.When water gains heat, it changes into water vapour. 1 cm3 of water forms more than 1000 cm3 of water vapour but the amount of particles (matter) in water remains the same.
Q. What can you infer or conclude from the information given above?
1. The mass of water increases when water changes into water vapour.
2. The spacing between the particles increases when water changes into water vapour.
3. Water can exist in three interchangeable states.
4. When water loses heat, it changes into ice.
A tank containing some aquatic plants is placed outdoors on a sunny day.Identify the factors that will affect, directly or indirectly, the amount of oxygen in the water.
1. The intensity of light in the water
2. The amount of plants in the tank
3. The material used for making the tank
4. The amount of carbon dioxide in the water
The diagram below shows the water cycle.
Q. Which of the following correctly shows heat gain or heat loss by water in Process A and Process B respectively?
The table below shows the melting and boiling points of substances P, Q, R and S.
Which substance(s) will change from gas to solid when there is a decrease in temperature from 200°C to 30°C?
The glass bowl below contains some ice cream. The bowl is left on the kitchen table at room temperature. After two minute, droplets of water appear on the outside surface of the glass and the ice cream starts to melt.
Q. Which of the following explains the changes observed?
1. The glass bowl condenses to form water droplets.
2. The ice cream gains heat from the surroundings.
3. The glass bowl gains coldness from the ice cream.
4. The metal spoon conducts heat from the surroundings to the ice cream.
5. The surrounding water vapour loses heat to the cooler surface of the glass bowl.
Pure and distilled water is not used for drinking, mainly because:
Saline water is useful for:
Saline solution for intravenous infusion. Saline, also known as saline solution, is a mixture of sodium chloride in water and has a number of uses in medicine. Applied to the affected area it is used to clean wounds, help remove contact lenses, and help with dry eyes. The medical use of saline began around 1831.
All the plants require nitrogen for:
Who am I, if:
1. I am present in the air
2. A human body needs me to produce energy
3. I enter your lungs when you breathe in
Study the classification chart below.
Q. Which of the following is correctly classified?
Abhilasha wanted to compare the time taken for different solutions to reach boiling point. She placed four beakers of different solutions over an electric stove and recorded the time taken for each of them to boil.
Q. Which of the following factors must she keep constant in order to carry out a fair test?
1. Size of the beaker
2. Amount of solution
3. Starting temperature of the solution
4. Final temperature of the solution
Which of the following about the water cycle is true?
Which of the following will change when water freezes?
A bowl contained 400 g of water. A 30 g cube of sugar was placed in the bowl of water and stirred until it dissolved completely.
After one day, it was found that only 400 g of the solution was left in the bowl. What would the remaining solution contain?
Chloe used the set-up below to study the property of air.
Q. What property/properties must the flask possess such that the balloon could be inflated quickly?
The water vapour in air is due to:
Hardness of water is due to the presence of:
Hard water, water that contains salts of calcium and magnesium principally as bicarbonates, chlorides, and sulfates. Water hardness that is caused by calcium bicarbonate is known as temporary, because boiling converts the bicarbonate to the insoluble carbonate; hardness from the other salts is called permanent.