Answer:
NaCl
Explanation:
because He which is helium gas its an element alone,
Cl which is chlorine is a single element,
B which is Boron and its a single element,
but NaCl which is simply called table sugar is the combination between Na, sodium and Cl, chlorine , so its called a compound not an element.
The number of protons is equal to the atomic number of every element in the periodic table.
Example: The atomic number of Niobium (Nb) is 41. Therefore, the number of protons is also 41.
Dumping waste is different from dilution and dispersion. Dumping waste is directly disposing your waste and not regulating its effect to the environment. Dilution is done usually before waste water disposal, meaning adding water to the waste to minimize its concentration.
Answer : The correct option is (3) 500 K and 0.1 atm.
Explanation :
A real gas behaves ideally at high temperature and low pressure.
The ideal gas equation is,

where,
P = pressure of gas
V = Volume of gas
R = Gas constant
T = temperature of gas
n = number of moles of gas
The ideal gas works properly when the inter-molecular interactions between the gas molecules and volume of gas molecule will be negligible. This is possible when pressure is low and temperature is high.
Therefore, the correct option is (3) 500 K and 0.1 atm.