Answer:
The answer to your question is V₁ = 12.5 ml
Explanation:
Data
Volume = V₁?
[NaOH] = C₁ = 4.0 M
Volume 2 = V₂ = 100 ml
[NaOH] = C₂ = 0.5 M
Formula of dilution
V₁C₁ = V₂C₂
Solve for V₁ (original solution)
V₁ = 
Substitution
V₁ = 
Simplification
V₁ = 
Result
V₁ = 12.5 ml
It depends on the plant you have. when you buy a new plant it usually has instructions so you would follow. Hope it helps!!!
16 H + + 2Cr2O72- + C2H5OH → 4 Cr3 + +11H2O +2CO2
The reducing agent is C2H5OH
Explanation
reducing agent is a substance that loses or donate electrons in a chemical reaction. C2H5OH is the one which donate electrons in the above chemical equation.
Answer: 4.18925 kJ heat is needed to convert 25.0 g of solid ethanol at -135 °C to liquid ethanol at -50°C.
Explanation:
Temperature of Solid
Melting temperature of Solid 
Temperature of liquid 
Specific heats of solid ethanol = 0.97 J/gK
Specific heats of liquid ethanol = 2.3 J/gK
Heat required to melt the the 25 g solid
at 159 K
= 159 K - 138 K = 21 K

Heat required to melt and raise the temperature of
upto 223 K
= 223 K - 159 K = 64 K

Total heat to convert solid ethanol to liquid ethanol at given temperature :
(1kJ=1000J)
Hence, 4.18925 kJ of heat will be required to convert 25.0 g of solid ethanol at -135 °C to liquid ethanol at -50°C.