Carbon and hydrogen are present in all
nitrogen is common
sulphur in proteins is common
oxygen is common in ethanoic acids
phosphorus is common for phosphate sugars
hope that helps
Explanation:
Given that,
The frequency of electromagnetic spectrum is 
(A) Let the wavelength of this radiation is 
. We know that,
So, the wavelength of this radiation is 
.
(B) Let E is the energy associated with this radiation. Energy of an electromagnetic radiation is given by :
h is Planck's constant
1 kcal = 4184 J
It means,
Hence, this is the required solution.
Answer:
A is the closest thing. You change the composition of the steak. You don't in any of the others.
Explanation:
Usually when you cook something, you are doing something to the composition of the object being cooked. A steak might not be obvious, but boiling an egg should be.
Chopping a tree is something physical. You are removing mass in such a way that the tree will fall. There's nothing chemical about that.
Heating a cup of tea looks like it might be chemical. After all steam is sometimes given off which looks like it is chemical. It's not. The water in the tea is just changing phase.
Drying clothes in a dryer. Again, this looks like something might have changed. After all the mass of the clothes just became less. But all you are doing is separating two masses (leaving one of them behind).
Answer:
Groups
Explanation:
Elements with the same number of valence electrons are found in the same column(group) of the Periodic Table.
Answer:
The answer is: (a) positive; (b) negative.
Explanation:
The change in enthalpy (ΔH) of a reaction is the amount of energy absorbed or released during a chemical reaction carried out at constant pressure.
a) In an endothermic chemical reaction, heat energy is absorbed by the system from the surrounding. Therefore, the sign of enthalpy change for an endothermic process is positive, ΔH= positive.
b) In an exothermic chemical reaction, heat energy is released by the system into the surrounding. Therefore, the sign of enthalpy change for an exothermic process is negative, ΔH= negative.
