Answer: 0.028 grams
Explanation:
Depression in freezing point :
Formula used for lowering in freezing point is,

or,

where,
= change in freezing point
= freezing point constant (for benzene} =
m = molality
Putting in the values we get:


0.028 grams of DDT (solute) must be dissolved in 209.0 grams of benzene to reduce the freezing point by 0.400°C.
Step 1 : write a valanced equation..
NaOH + HCl 》NaCl + H2O
Step 2 : find the number of mole of HCl..
1000 ml ..contains 4.3 mole
15ml... (4.3÷1000)×15 =...
Stem 3 : use mole ratio....
HCl : NaOH
1 : 1
So mole is same as calculated above...
Step 4 :
3.5 mole of NaOH is in 1000ml
(4.3÷1000)×15 mole is in ....
Do the calculation
Visible light spectrum.
The visible light spectrum is part of the electromagnetic radiation spectrum