We can answer this one very quickly. From the <em>Law of Conservation of Energy</em>, we know that "Energy can't be created or destroyed.".
So that only leaves us one way to complete the sentence in this question:
"One form of energy can be <em>transformed into</em> another type of energy.
" <em>(B)</em>
I dont know the answer i just want brainy points<span />
The heat required to convert the unknown substance X from one phase to another is 1600 J times the specific heat of that substance.
Explanation:
The heat energy required to convert a substance or to heat up or increase the temperature of a substance can be obtained from the specific heat formula.
As per this formula, the heat energy applied should be equal to the product of mass of the substance with temperature gradient and also with specific heat of the substance. Basically, the heat provided to increase or convert a substance should be more than the specific heat of the substance.

Since, here the mass of the substance X is given as m = 20g and the temperature change is given from -10°C to 70°C.
Then ΔT = (70-(-10))=70+10=80°C.
As the substance is unknown, the specific heat of that substance can also not be determined. Hence keep it as C.

Q = 1600C J
Thus, the heat required to convert the unknown substance X from one phase to another is 1600 J times the specific heat of that substance.
Answer:
Wavelength of electromagnetic wave will be 5.281 m
Explanation:
We have given frequency of electromagnetic wave is 
Velocity of electromagnetic wave is 
We have to fond the wavelength of the electromagnetic wave
We know that velocity of electromagnetic eave is given by
, here
is wavelength and f is frequency
So 
Wavelength of electromagnetic wave will be 5.281 m