English Medium कक्षा १० - CBSE Important Questions

Find the area of the shaded region in Fig. 3, where arcs drawn with centres A, B, C and D intersect in pairs at mid-points P, Q, R and S of the sides AB, BC, CD and DA respectively of a square ABCD of side 12 cm. [Use π = 3.14]

The diameters of the lower and upper ends of a bucket in the form of a frustum of a cone are 10 cm and 30 cm respectively. If its height is 24 cm, find:

1) The area of the metal sheet used to make the bucket.

2) Why we should avoid the bucket made by ordinary plastic? [Use π = 3.14]

A vessel is in the form of hemispherical bowl surmounted by a hollow cylinder of same diameter. The diameter of the hemispherical bowl is 14 cm and the total height of the vessel is 13 cm. Find the total surface area of the vessel. `[\text{Use}pi=22/7]`

The total surface area of a solid hemisphere of radius 7 cm is ______.

Khurja is a city in the Indian state of Uttar Pradesh famous for the pottery. Khurja pottery is traditional Indian pottery work which has attracted Indians as well as foreigners with a variety of tea sets, crockery and ceramic tile works. A huge portion of the ceramics used in the country is supplied by Khurja and is also referred as "The Ceramic Town". One of the private schools of Bulandshahr organised an Educational Tour for class 10 students to Khurja. Students were very excited about the trip. Following are the few pottery objects of Khurja. Students found the shapes of the objects very interesting and they could easily relate them with mathematical shapes viz sphere, hemisphere, cylinder etc.

Maths teacher who was accompanying the students asked the following questions:

1. The internal radius of hemispherical bowl (filled completely with water) in I is 9 cm and the radius and height of the cylindrical jar in II are 1.5 cm and 4 cm respectively. If the hemispherical bowl is to be emptied in cylindrical jars, then how many cylindrical jars are required?
2. If in the cylindrical jar full of water, a conical funnel of the same height and same diameter is immersed, then how much water will flow out of the jar?

With the help of an appropriate example, justify that some of the chemical reactions are determined by the evolution of a gas.

Give a chemical equation for the reaction involved in the above case.

With the help of an appropriate example, justify that some of the chemical reactions are determined by a change in colour.

Give a chemical equation for the reaction involved in the above case. 

With the help of an appropriate example, justify that some of the chemical reactions are determined by a change in temperature.

Give a chemical equation for the reaction involved in the above case.

State the change in colour observed in the following case, mentioning the reason:

Silver chloride is exposed to sunlight.

Answer the following question.
2 g of silver chloride is taken in a china dish and the china dish is placed in sunlight for some time. What will be your observation in this case? Write the chemical reaction involved in the form of a balanced chemical equation. Identify the type of chemical reaction.

Answer the following question.
What is observed when 2 mL of dilute hydrochloric acid is added to 1 g of sodium carbonate taken in a clean and dry test tube? Write a chemical equation for the reaction involved.

In a double displacement reaction such as the reaction between sodium sulphate solution and barium chloride solution:

1. exchange of atoms takes place
2. exchange of ions takes place
3. a precipitate is produced
4. an insoluble salt is produced

The correct option is:

When aqueous solutions of potassium iodide and lead nitrate are mixed an insoluble substance separates out. The chemical equation for the reaction involved is: 

What is observed when silver chloride is exposed to sunlight? Give the type of reaction involved.

Bronze is an alloy of ______.

Select the appropriate state symbols of the products given as X and Y in the following chemical equation by choosing the correct option from table given below: 

\[\ce{Zn_{(s)} + H_2SO_{4(l)} ->ZnSO_{4(X)} + H_{2(Y)}}\]

Give the structural formula of ethanol.

In an experiment to study the properties of ethanoic acid, a student takes about 3 mL of ethanoic acid in a dry test tube. He adds an equal amount of distilled water to it and shakes the test tube well. After some time he is likely to observe that

(A) a colloid is formed in the test tube.

(B) the ethanoic acid dissolves readily in water.

(C) the solution becomes light orange.

(D) water floats over the surface of ethanoic acid.

While studying saponification reaction, a student measures the temperature of the reaction mixture and also finds its nature using blue/red litmus paper. On the basis of his observations the correct conclusion would be

(A) the reaction is exothermic and the reaction mixture is acidic.

(B) the reaction is endothermic and the reaction mixture is acidic.

(C) the reaction is endothermic and the reaction mixture is basic.

(D) the reaction is exothermic and the reaction mixture is basic.

What are covalent compounds?