A tree getting struck by lightning, it is an example of a physical change.
It is so because when a tree getting struck by lightning, it encountered a strong force of power but no new substance is formed here. So it is a physical change, if it is a chemical change then a new substance must formed here. So when a tree getting struck by lightning, it is an example of a physical change.
CH₃ - C≡C - CH₃
2-butyne or but-2-yne
:)
Answer: 9.08 L
Explanation:
To calculate the moles :

According to stoichiometry :
4 moles of
require = 3 moles of 
Thus 0.54 moles of
will require=
of 
Standard condition of temperature (STP) is 273 K and atmospheric pressure is 1 atm respectively.
According to the ideal gas equation:

P = Pressure of the gas = 1 atm
V= Volume of the gas = ?
T= Temperature of the gas = 273 K
R= Gas constant = 0.0821 atmL/K mol
n= moles of gas= 0.405

Thus 9.08 L of
at STP would be required
A neutral sodium atom, for example, contains 11 protons and 11 electrons. By removing an electron from this atom we get a positively charged Na+ ion that has a net charge of +1. Atoms that gain extra electrons become negatively charged. A neutral chlorine atom, for example, contains 17 protons and 17 electrons.
The answer is each indicator has a narrow range. We need many different indicators to span the entire ph spectrum because each indicator has a narrow range.