Railway Science (Chemistry-Miscellaneous) (Part-III)

Total Questions: 27

1. The melting and boiling points of ionic compounds are ________. [RRB Group D 11/10/2018 (Evening)]

Correct Answer: (a) high
Solution:

Ionic compounds are composed of positively and negatively charged ions held together by strong electrostatic forces of attraction, known as ionic bonds. These bonds are very strong, requiring a significant amount of energy to overcome in order to change the state of the compound from solid to liquid (melting) or from liquid to gas (boiling).

2. Which of the following statements is true ? [RRB Group D 12/10/2018 (Morning)]

A. Size: Depending on the type of substance, size varies depending on the location of the particles. For example, solids have a definite shape while liquids take the shape of their container and gasses have no shape.
B. Compressibility: It is the property of a substance that flows easily and allows its shape to change under external forces and this property is exhibited by both liquids and gasses.

Correct Answer: (b) Only A is true.
Solution:

Compressibility is a fundamental property of matter that describes how much its volume can change under an applied pressure. It essentially measures how easily the particles within a substance can be squeezed closer together.

3. In CaO, the ratio of Ca and O by mass is ______. [RRB Group D 15/10/2018 (Morning)]

Correct Answer: (a) 5 : 2
Solution:

The atomic mass of calcium = 40 u. The atomic mass of Oxygen = 16 u. Ratio by mass of Calcium (Ca) and Oxygen (O) in CaO = 40 : 16 = 5 :2

4. Dalton's nuclear theory provides an explanation for which of the following? [RRB Group D 23/10/2018 (Afternoon)]

Correct Answer: (b) Law of mass conservation and definite proportions
Solution:

Law of definite proportions: This law states that a given compound always contains the same elements in the same fixed proportion by mass. Law of conservation of mass: This law states that the total mass of reactants in a chemical reaction must equal the total mass of products.

5. _____ polymers are used in making floor tiles. [RRB Group D 26/10/2018 (Afternoon)]

Correct Answer: (a) Poly vinyl chloride
Solution:

Poly vinyl chloride (PVC): Monomer - Vinyl chloride. Uses - Manufacture of rain coats, hand bags, vinyl flooring, water pipes. The term polymer is defined as very large molecules having high molecular mass (10³ -10⁷u). Some Other Commercially Important Polymers: Polypropene - Used in Manufacture of ropes, toys, pipes, fibres, etc. Polystyrene - As insulator, wrapping material, manufacture of toys, radio and television cabinets.

6. 16 g of oxygen has ______ atoms of oxygen. [RRB Group D 29/10/2018 (Evening)]

Correct Answer: (c) 6.022 × 10²³
Solution:

Oxygen is the chemical element with the symbol O and atomic number 8, Atomic weight 15.9994, Density of 1.429g/L. Oxygen is made of three stable isotopes - O-16, O-17, and O-18. O-18 is the most abundant isotope of oxygen. Oxygen is the most plentiful element in Earth’s crust.

7. Chemical fertilizers improve the yield, but after some seasons, the yield may decrease due to poor soil quality. Which of the following can be used to improve soil quality ? [RRB Group D 3/12/2018 (Afternoon)]

Correct Answer: (a) slaked lime
Solution:

Soil acidity can be corrected by liming. Lime is applied into soil at the time of and preparation or in ploughed land. About 1,500 kg lime per hectare is required to raise the pH of the soil by one unit.
Limestone, burnt lime or slaked lime can be used to correct the acidity of the soil. Lime increases phosphorus, nitrogen, potassium and molybdenum content in the soil.

8. Which of the following metals is used to electrode iron material ? [RRB Group D 07/12/2018 (Afternoon)]

Correct Answer: (c) Silver
Solution:

Electrode material refers to a substance that can be used as an electrode. The electrode, metallic or non-metallic, can be divided into positive electrode and negative electrode. Some of the most prominent alloys and materials used as electrode materials are copper, graphite, titanium, brass, silver, and platinum.

9. All samples of carbon dioxide contain carbon and oxygen in the mass ratio of 3:8. This is in agreement with the _____rule. [RRB Group D 10/12/2018 (Morning)]

Correct Answer: (c) constant proportion
Solution:

It is also known as the law of definite proportions. This law was stated by Proust as “In a chemical substance the elements are always present in definite proportions by mass”.
In a compound such as water, the ratio of the mass of hydrogen to the mass of oxygen is always 1 : 8, whatever the source of water. Similarly in ammonia, nitrogen and hydrogen are always present in the ratio 14 : 3 by mass.

10. What is the unit of ionization energy ? [RRB Group D 12/12/2018 (Afternoon)]

Correct Answer: (c) KJ mol⁻¹
Solution:

Ionization energy is the energy required to remove an electron from one mole of gaseous atoms. Units = 𝐸𝑛𝑒𝑟𝑔𝑦/𝑀𝑜𝑙 = 𝐾𝐽/𝑀𝑜𝑙 = KJ mol⁻¹ .