Saleha Pervez, Mansi Garg and, Poonam Singh Solutions for Chapter: Elements and Compounds, Exercise 1: Self Check

Which one among the following is called philosopher's wool?

Which one of the following does not contain silver?

Which are the materials generally employed as solder in soldering operation in electronics?

Which of the following substances are found in the beach sands of many parts of Kerala?
$1.$ Ilmenite
$2.$ Zircon
$3.$ Sillimanite
4. Tungsten 

Select the correct answer using the codes below.

Graphene is frequently in the news recently. What is its importance?
1. It is a two-dimensional material and has good electrical conductivity.
2. It is one of the thinnest but strongest materials tested so far.
3. It is entirely made of silicon and had high optical transparency.
4. It can be used as 'conducting electrodes' required for touch screens, LCDs and organic LEDs.
Which of the statement(s) given above are correct?

Consider the following statements regarding pH value,

1. Plants and animals are pH sensitive as they survive within the pH range of 7.0 to 7.8.

2. Human blood has pH value 7.36-7.42.

3. A change in pH of blood by 0.2 units results in death.

Which of the statement(s) given above is/are correct?

Consider the following statements,

1. The mixture of helium and oxygen is used for artificial breathing of asthma patient.

2. Solution of$\frac{Kl}{I2}$ is used in the treatment of goitre.

Which of the statement(s) given above is/are correct?

Consider the following statements about calcium:

1. It forms basic oxide with air.

2. It floats over water.

3. It replaces sodium from sodium chloride.

The incorrect statement(s) is/are: