Explanation:
( a )
<u>The four types of spread spectrum techniques are as follows -</u>
1. Direct sequence spread spectrum .
2. frequency hopping spread spectrum .
3. chirp spread spectrum .
4. time hopping spread spectrum .
( b )
<u>The Direct sequence spread spectrum was devised for eavesdropping in the military .</u>
In the field of telecommunications , the Direct sequence spread spectrum , it is the technique of spread spectrum modulation which is used to reduce the overall inference of the signal .
Answer:
the three products of destructive distillation of coal are:-
1. coal gas
2. coke
3. ammonia liquor
The product of reduction of ethyl 4-oxobutanoate with sodium borohydride in ethanol at room temperature for 30 minutes is ethyl 4- hydroxybutanoate .
Sodium borohydride is a relatively selective reducing agent Ethanolic solutions of Sodium borohydride reduces aldehyde , and ketone , in the presence of acid chloride , ester , epoxide , lactones , acids , nitriles , nitro groups.
The sodium borohydride does not reduce ester group because sodium borohydride is not strong enough and the electrophilicity at carbony carbon of ester is not more as compare toaldehyde , and ketone
The product of reduction of ethyl 4-oxobutanoate with sodium borohydride in ethanol at room temperature for 30 minutes is ethyl 4- hydroxybutanoate .
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Acid rain<span> is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as </span>acid rain<span>.</span>
Balanced chemical reaction: 2KCl + Pb(NO₃)₂ → PbCl₂ + 2KNO₃.
According to principle of mass conservation, number of atoms must be equal on both side of balanced chemical reaction.
KCl is potassium chloride.
Pb(NO₃)₂ is lead(II) nitrate.
KNO₃ is potassium nitrate.
PbCl₂ is lead(II) chloride.
