Answer:
a) KOH
Explanation:
In the given balanced reaction
2K + 2H2O → 2KOH + H2
In the compound KOH,
The elements are K,O, and H and in the compound, there is one mole each of K , O ,and H.
So the element ratio here is 1 : 1 : 1.
Answer: a) 
b) 
Explanation: Visible light is a form of electromagnetic wave.
Wavelength is defined as the distance between two successive crests of a wave. It is represented as symbol
.
Frequency is defined as the number of complete cycles happening per second. It is represented by the symbol
.
Wavelength and Frequency follow inverse relation,

where, c = speed of light = 
Wavelength and frequency of a wave is usually expressed in a range.
a) 
b) 
Answer:
a) 40,75 atm
b) 30,11 atm
Explanation:
The Ideal Gas Equation is an equation that describes the behavior of the ideal gases:
PV = nRT
where:
- P = pressure [atm]
- V = volume [L]
- n = number of mole of gas [n]
- R= gas constant = 0,08205 [atm.L/mol.°K]
- T=absolute temperature [°K]
<em>Note: We can express this values with other units, but we must ensure that the units used are the same as those used in the gas constant.</em>
The truncated virial equation of state, is an equation used to model the behavior of real gases. In this, unlike the ideal gas equation, other parameters of the gases are considered as the <u>intermolecular forces</u> and the <u>space occupied</u> by the gas

where:
- v is the molar volume [L/mol]
- B is the second virial coefficient [L/mol]
- P the pressure [atm]
- R the gas constant = 0,08205 [atm.L/mol.°K]
a) Ideal gas equation:
We convert our data to the adecuate units:
n = 5 moles
V = 3 dm3 = 3 L
T = 25°C = 298°K
We clear pressure of the idea gas equation and replace the data:
PV = nRT ..... P = nRT/V = 5 * 0,08205 * 298/3 =40,75 atm
b) Truncated virial equation:
We convert our data to the adecuate units:
n = 5 moles
V = 3 dm3 = 3 L
T = 25°C = 298°K
B = -156,7*10^-6 m3/mol = -156,7*10^-3 L/mol
We clear pressure of the idea gas equation and replace the data:

and v = 3 L/5 moles = 0,6 L/mol

The correct answer would be 3.) Location of an electron