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A substance 'X' is bitter in taste. The chemical nature of the substance could be:

Appu’s father wants to grow onions on his farm. Appu’s farm has three kinds of soil in different areas. Onions grow best in loamy soil. So, Appu decided to measure the percolation rate for the three different soils on his farm. He used a device like the one shown below. Appu, however, forgot and added different quantities of water while testing the percolation rate for each soil. He measured the time taken for all the water added to the device to percolate and tabulated them.

$\begin{array}{ccc}\text{Soil Number}& \text{Quantity of water added}& \text{Time taken to percolate completely}\\ \text{Soil 1}& \text{500 mL}& \text{300 minutes}\\ \text{Soil 2}& \text{200 mL}& \text{30 minutes}\\ \text{Soil 3}& \text{100 mL}& \text{300 minutes}\end{array}$

Which soil must be used to grow onions?

When washing soda is treated with hydrochloric acid, it gives off colourless gas with lot of effervescence, then that gas is

A mixture of milk and groundnut oil can be separated by ___.

Which of the following is/are a crystalline form of carbon?

Natural air contains oxygen, nitrogen and carbon dioxide in the ratio 12 : 5 : 3. Find the percentage of nitrogen in the air.

The sting of the ant contains which of the following?

Isotopes of the same element have

Seema was reading about water scarcity. She started wondering what measures she should take to reduce water wastage. Which of the following measure should Seema take?

An experiment was performed to know about the source of air for the aquatic organisms. The experiment was as follows:

Take some water in a glass vessel. Heat it slowly on a tripod stand. Before the water begins to boil, look carefully at the inner surface of the vessel. Observe the bubbles that are coming up. Where are these bubbles coming from?

Balanced equation of calcium oxide with water

Bile and pancreatic juice change the pH of the chyme in the small intestine. what change occurs in the pH? can you explain the requirement of changing the pH from the perspective of enzyme requirements?

There are two tubs full of water, A and B.
The water in tub A contains ${\text{MgCl}}_2$ salts in very low concentration. Tub B on the other hand contains ${\text{MgCl}}_2$ salts in high concentration. Clothes are washed using water from these tubs separately. The clothes washed using water from which of the two tubs will be cleaner?

Why different fabrics are weaved differently?

Identify the type of wool produced from the goats shown in the picture below which produce high quality wool used to make shawls and other clothing.

Question 7 (c)
Fill in the blank:
(c) Herbs form the __ layer in the forest.

Saturation with which of the following substances will produce hard water?

What kind of clothes shouldn't be worn in kitchen and laboratories

Excessive intake of foods containing sugar is a major cause of

What is fungi

What can we do to save water from pollution?

Most of the electricity-carrying wires along the roads do not have a plastic covering like the wires used at homes. But why is there no substantial loss of energy?

Carbon in wood reacts with oxygen in the air to give carbon dioxide gas.
Which among the following is the correct representation of this chemical reaction?

Elsa loves ice creams and makes it at home.One day she invited her friends for an ice cream party but unfortunately there was a power cut for 3 hours and the ice cream she prepared melted down. Which type of change is the melting of ice?

Stainless steel is an alloy of iron with:

Consider the following reaction.
$CaC{O}_3+H_{2}O+C{O}_2\to Ca(HC{O}_3{)}_2$

$\begin{array}{cc}\text{Element}& \text{Number of atoms present}\end{array}$
$\begin{array}{ccc}& \text{Reactant side}& \text{Product side}\\ \text{Calcium}& 1& 1\\ \text{Carbon}& 2& Y\\ \text{Oxygen}& X& 6\\ \text{Hydrogen}& 2& 2\end{array}$
Recognise $X$ and $Y$. The value of $X+Y$ is___.

Once wastewater is slowed down, it is let into large settlement tanks. Which of the following contaminants are removed as sludge in this process? (You may choose more than one option).

Classify the following as physical and chemical changes:
(i) Eraser used for deleting pencil marks
(ii) Cooking of food items
(iii) Formation of clouds
(iv) Making ice candy

Cooking of rice is a chemical change.

The alkali metal which can directly unite with nitrogen is

While roaming in the zoo Stephan asked his grandfather, "What is the difference between a zoo and a sanctuary? "

Explain what happens when food particles remain in mouth after eating. How can we prevent the effect?

Arnav is provided with three kinds of liquid of them one is sodium hydroxide; another is hydrochloric acid and third is a sugar solution. How will he identify them when he have only turmeric indicator?

$2H_2+O_2\to 2H_{2}O$

What can be infered from the above equation?

What are the advantages of vermi-processing toilets? [2 MARKS]

Find odd one out - water, ice, water vapour, aquifer

Explain the process of formation of iron oxide . Can you name this process of oxidation? Suggest measures how this can be prevented ? [5 MARKS]

It is very interesting to know that our body is made up of various acids. Each cell in our body contains acids. Can you think of an acid which is present in every cell and controls our looks, the colour of our eyes, our height and so on?

Which of the following exists as a non-reactive gas at room temperature?

The movement of molecules of matter from a region of higher concentration to a region of lower concentration is called ___

An atom is made up of

Which of the following is physical change?