2nd Year Chemistry Chapter 15 Common Chemical Industries In Pakistan Short And Simple Question & Answer
Q.1 What are the macronutrients of plants?
Ans. Macronutrients are those elements that are needed in large quantities for the growth of plants. Nitrogen, phosphorous, and potassium are macronutrients. The quantity required per acre is 5 to 200 kg.
Q.2 What are the micronutrients of plants?
Ans. The elements required in small quantities for plant growth are called micronutrients. Copper, manganese, zinc, boron iron, molybdenum, and chlorine are micronutrients. The quantity required per acre ranges from 6 g to 200 g.
Q.3 Why prilled urea is better than a fine powder?
Ans. The conversion of urea into granules is called prilling. Prilled urea spreads on crops more easily than a fine powder. The powder can stay on the leaves of plants while granules do not.
Q.4 Ammonium nitrate is not a useful fertilizer for paddy rice, why?
Ans. Pladdy rice requires a greater quantity of water. Microbial bacteria in flooded fields decompose ammonium nitrate into nitrogen gas.
Q.5 Which crops require more potassium fertilizers?
Ans. Tobacco, coffee, potato, and corn require more potassium fertilizers.
Q.6 Which raw materials are used for cement?
Ans. Important raw materials for the cement industry are (i) calcareous material; limestone, marble, chalk marine shells. (ii) argillaceous materials, clay, shale, slate. (iii) gypsum.
Q.7 Why do we call cement Portland cement?
Ans. In 1824, Joseph Aspdin prepared cement by heating limestone and clay. When it is mixed with water it changes to a hard mass. This hard mass has a resemblance with the stones of a famous building material obtained from the island of Portland near England.
Q.8 Is cement a mixture or compound?
Ans. Cement is a mixture of many compounds and each compound has its characteristic properties. The final properties of cement depend upon the composition of cement.
Q.9 Which process is mostly used for the manufacturing of cement in Pakistan?
Ans. There are two manufacturing processes for cement (i) dry process and (ii) wet process. The choice of the dry or wet process depends upon the physical conditions of raw materials, the local climatic conditions of the factory, and fuel prices. In Pakistan, mostly wet process is used. The wet process is free from dust, grinding is easier, and the composition of cement can easily be controlled. Ans.
Q.10 Write the name of different zones and their temperature in the rotary kiln.
Ans. There are four zones:
(i) Drying zone (500°C)
(ii) Decomposition zone (800°C)
(iii) Burning zone (1500°C)
(iv) Cooling zone (150-200°C)
Q.11 What are clinkers?
Ans. The product obtained from the rotary kiln is known as clinker. They are greenish-black or grey-colored balls varying in size from small nuts to peas. This clinker is mixed with 4 to 5% gypsum and finally ground product is called cement.
Q.12 Write the names of processes that are used for pulp making?
Ans. (i) Kraft process
(ii) Sulphite process
(iii) Neutral sulphite semi-chemical process (NSSC)
Q.13 Write the names of woody and non-woody raw materials for pulp making?
Ans. Woody materials are poplar, eucalyptus, and fur. Non-woody are wheat straw, corn straw, and rice straw.
Q.14 Which bleaching agents are used to bleach the pulp in Pakistan?
Ans. The pulp obtained from the digester is brown and not suitable for writing paper. The pulp is bleached with ClO2 or sodium hypochlorite (NaCIO).
Q.15 What is the role of additives in paper making?
Ans. Additives increase the mechanical strength of paper and reduce the pores of the paper. They increase the glaze of the paper.
Q.16 What is the role of the headbox in papermaking, the Fourdrinier machine?
Ans. The headbox discharges a uniform jet of pulp suspension on a fabric. The water of the pulp is removed.
Q.17 What is calendering in paper making?
Ans. The size of the paper sheet is reduced in thickness by the help of nip rolls. The surface of the paper becomes smooth and pores are reduced. This process is called calendering.