It's 1. Melting a substance. The rest are chemical changes
Answer: 33.3 moles
Explanation: 67.2 g H2 = 67.2/2.016 = 33.3 moles
Answer:
4. 60 neutrons.
Explanation:
The given isotopes;
¹⁰⁶₄₆Pd
In this isotope, we can deduce that the mass number is the superscript and the atomic number is the subscript;
Mass number = 106
Atomic number = 46
Mass number is the number of protons and neutrons in an atom;
Mass number = Protons + neutrons
Atomic number is the number of protons
So, Number of protons = 46
Number of neutrons = Mass number - Atomic number
= 106 - 46
= 60
Number of neutrons = 60
Answer:
The activation energy for an endothermic reaction is quite large and usually takes extra energy from the environment, it is normally not a natural spontaneous process.
Explanation:
- Endothermic reactions require absorbing energy of the surrounding mainly in the form of heat.
- Chemical energy needs energy input to break the bonds.
- Examples of endothermic reactions: Photosynthesis
, melting of ice
, and evaporating liquid water.
