MCQ
301. Le-chatelier apparatus used to perform- [BPSC-20]
Fineness test
Soundness test
Consistency test
Compressive strength test
ব্যাখ্যা: ব্যাখ্যা:
সিমেন্টের সাউন্ডনেস টেস্ট করা জন্য ব্যবহৃত যন্ত্রের নাম Le-chatelier apparatus.
302. Calculate standard consistency (%) when 100ml if water is added in 1kg of cement-----[BB-20]
10
1000
100
1
ব্যাখ্যা: ব্যাখ্যা: Standard Consistency (%) = (wt of water added/wt of cement) x 100
=(100/1000)x100=10
303. If water cement ratio decrease, compressive strength of concrete will-. [MOD-20]
increase
decrease
no change
increase
ব্যাখ্যা: ব্যাখ্যা: The water-cement ratio is the ratio of the weight of water to the weight of cement used in a concrete mix. A lower ratio leads to higher strength and durability, but may make the mix difficult to work with and form. Workability can be resolved with the use of plasticizers.
304. The chief ingredient of a paint is---- [MOD-20]
thinner
alcohol
drier
pigment
ব্যাখ্যা: ব্যাখ্যা: A pigment is a colored material that is completely or nearly insoluble in water. Generally dyes are often organic compounds whereas pigments are often inorganic compounds. Pigments of prehistoric and historic value include ochre, charcoal, and lapis lazuli.
305. The coefficient of hardness of stones used in road works should not be greater than : [PPA-20]
10
12
15
17
ব্যাখ্যা: ব্যাখ্যা:
The coefficient of hardness of stone between 14-17 for building purpose and greater than 17 is used for road.
306. Granite is an example of- [MES-18, MOD-20]
aqueous rocks
sedimentary rock
metamorphic rocks
igneous rocks
ব্যাখ্যা: ব্যাখ্যা: The rocks in which clay content is predominant are called argillaccous rock. (আগ্নেয় শিলা) The rocks are soft in nature and with the presence of water they can be crumbled easily some of the argillaceous rocks are
shale, slate, kaolin, literate etc.
307. What is the specific gravity of cement? [MOD-20]
3.50
2.67
2.15
3.15
ব্যাখ্যা: ব্যাখ্যা: The specific gravity is normally defined as the ratio between the weight of a given volume of material and weight of an equal volume of water. The portland cement have a specific gravity of value around 3.15. Specific gravity of cement is ranging between 3.1-3.16 g/cc.
308. The clinker is formed at a temperature of-(MOD-20)
500°C
1000°C
1200°C
1500°C
ব্যাখ্যা: ব্যাখ্যা: Portland cement clinker is made by heating a homogeneous mixture of raw materials in a rotary kiln at high temperature. The products of the chemical reaction aggregate together at their sintering temperature, about 1,500°C (2,732°F).
309. Efflorescence is caused if-. [MOD-20]
the alkaline salt is present in the bricks
the clay used for making bricks contain pyrite
the water used for pugging the clay contain gypsum
all of the above
ব্যাখ্যা: ব্যাখ্যা: Three factors must be present wherever efflorescence appears:
A soluble salt: A variety of salts and salt-forming chemicals can be present in masonry.
Water: Moisture is the vehicle that carries the salt 10
the surface of the masonry.
Channels: Concrete and bricks have microscopic pores. These tiny channels allow water to move by
wicking action.
310. Seasoning of timber-. [MOD-20]
increase the weight of timber
improves strength properties of timber
does not give dimensional stability
all of these
ব্যাখ্যা: ব্যাখ্যা: The process by which removal of excess moisture content from the timber at a suitable level in conjunction with improving strength is known as seasoning of timber.
311. Which of the following is the purest form of iron? [BB-20]
Cast iron
Wrought iron
Mild steel
High carbon steel
ব্যাখ্যা: ব্যাখ্যা: Wrought iron is the purest from of iron. It contains 0.12 to 0.25% carbon and is thus the purest from of iron.
312. Soundness of cement is tested by- [BB-20]
Vicats appararus
Le-chatelier apparatus
Compressive strength testing apparatus
none of these
ব্যাখ্যা: ব্যাখ্যা: Soundness of cement may be determined by two methods, namely le-chatelier method and autoclave method,
Soundness of cement is tested by le-chatelier apparatus.
313. Good quality of cement should have higher percentage of-. [MOD-20]
silica
free lime
di-calcium silicate
tri-calcium silicate
ব্যাখ্যা: ব্যাখ্যাঃ tri-calcium silicate-50%
di-calcium silicate-30%
tri-calcium aluminates-10% 1520
Teira calcium-10%
gypsum-5%
314. French polish is- [PPA-20]
Oil paint
Distemper
Spirit varnish
Asphalt
ব্যাখ্যা: ব্যাখ্যা: Oil paint is a type of slowdrying paint that consists of particles of pigment suspended in a drying oil, commonly linseed oil.
315. Which one is the fine aggregate? [MOD-20]
cement
sand
khoa
lime
ব্যাখ্যা: ব্যাখ্যা: Sand, surki, stone screenings, burnt clays, cinders, fly ash etc. are used as fine aggregate in concrete.
316. Quick lime on reacting with water gives- [MOD-20]
hydraulic lime
hydrated lime
poor lime
slaked lime
ব্যাখ্যা: ব্যাখ্যা: When quick lime is added to water, it reacts to jomm calcium hydroxide (slaked lime). CaO(s) + H2O(l) → Ca(OH)2 (aq) + heat
Quick lime Slake lime
317. Oil point-এর ক্ষেত্রে সাধারণত Solvent হিসাবে ব্যবহার করা হয়- [BPSC-20]
Linseed oil
Turpentine
Naptha
Kerosene
ব্যাখ্যা: ব্যাখ্যা: Oil paint-এর সাথে Turpentine মিশ্রণের মাধ্যমে Paint- কে ব্যবহার উপযোগী করা হয়, কারণ Oil paint-এর Solvent হিসাবে Water মিশ্রিত করা যায় না। Oil paint-কে পাতলা বা নরম করার জন্য Solvent হিসাবে Turpentine ব্যবহার করা হয়।
318. Which of the following cements is suitable for use in massive concrete structures such as large dams? [BB-20]
Ordinary Portland cement
Low heat cement
Rapid hardening cement
Sulphate resisting cement
ব্যাখ্যা: ব্যাখ্যা: Low heat cement is one of the hydraulic binding materials and would always be perferred for massive structures such as dams. It has excellent performance such as high final strength, long lasting properties.
319. Gypsum is added in the manufacture of Portland cement in order to- [MOD-20]
shorten the setting time of cement
lengthen the setting time of cement
decrease the burning temperature
decrease the grinding time
ব্যাখ্যা: ব্যাখ্যা: Gypsum plays a very important role in controlling the rate of hardening of the cement. During the cement manufacturing process, upon the cooling of clinker, a small amount of gypsum is introduced during the final grinding process. Gypsum is added to control the "setting of cement".
320. [MOD-20] What is the unit weight of water?
50 Ib/ft²
62.5 Ib/ft²
90.5 Ib/ft^3
100 lb/ft^3
ব্যাখ্যা: ব্যাখ্যা: The specific weight, also known as the unit weight, is the weight per unit volume of a material. A commonly used value is the specific weight of water on Earth at 4°C, which is 9.807 kN/m² or 62.5 Ibf/ft².