NHPC JE'21 ME: Daily Practices Quiz. 20-Oct-2021

Quiz: Mechanical Engineering
Exam: NHPC JE
Topic: Material Science

Each question carries 1 mark
Negative marking: 1/4 mark
Time: 6 Minutes

Q1. Allotrope of a material means
(a) Its atoms distributed in random patterns
(b) Its atoms distributed in fixed pattern
(c) It has different crystal structure at different temperatures
(d) It has fixed structure at all temperatures

Q2. Toughness of a material indicates
(a) Strength of material
(b) Fatigue Resistance of material
(c) Machinability of material
(d) Softening of material

Q3. The number of atoms in an HCP crystal structure are?
(a) 8
(b) 4
(c) 6
(d) None of these

Q4. In equilibrium at eutectic point of an iron carbon diagram, the number of phases present is
(a) 0
(b) 1
(c) 2
(d) 3

Q5. Pearlite is a
(a) Combination of Ferrite and cementite
(b) Combination of Cementite and gamma iron
(c) Combination of Ferrite and austenite
(d) Combination of Ferrite and iron graphite

Q6. The hardening of machine tool guide ways is usually carried out by
(a) flame hardening
(b) induction hardening
(c) vacuum hardening
(d) furnace hardening

Solutions

S1. Ans. (c)
Sol. Allotrope of material means it has different crystal structure at different temperatures.

S2. Ans. (a)
Sol. Toughness of a material is the ability to absorb energy when the material is under plastic deformation up to fracture.
So, toughness is good combination of strength and ductility and it is the area under the stress strain curve upto fracture from a tensile test.

S3. Ans. (c)
Sol. The hexagonal closed packed (HCP) has number of atoms 6 per unit cell and coordination number 12.

S4. Ans. (d)
Sol. In equilibrium at eutectic point of an iron carbon diagram, the number of phases present is 3.

S5. Ans. (a)
Sol. Pearlite is combination of of 87% ferrite which is thick layer and 13% cementite which thin layer and are arranged alternatively in a lamella formation.

S6. Ans. (a)
Sol. The hardening of machine tool guide ways is usually carried out by flame hardening.