5 electrons
Boron atomic number 5 has five electrons in its ground state.
Commonly Boron will lose 3 electrons leaving 2 electrons in its most common ionic form.
Explanation:
The atomic number gives the number of protons. Protons which have a positive charge are balanced by an equal number of electrons in a neutral atom.
Boron number 5 has five protons and therefore as a neutral atom also has five electrons.
Boron has an electron configuration of 
1s22s22p1
The most stable electron configuration for Boron is
1s2
 + 3 charges. By losing three electrons Boron can achieve the stable electron structure of Helium
Brainliest? :D
 
        
             
        
        
        
Answer:
Number of moles of chlorine = 3.38 mol
Explanation:
Given data:
Mass of chlorine = 120 g
Moles of chlorine = ?
Solution:
Formula:
Number of moles = mass/molar mass
Molar mass of chlorine = 35.5 g/mol
Now we will put the values in formula.
Number of moles = 120 g/ 35.5 g/mol
Number of moles = 3.38 mol
 
        
             
        
        
        
Transform the g into kg by multiplying 0.74 by 10^-3. then divide 2.4 kg by the density
 
        
        
        
Answer:
32
Explanation:
The vapour density of a gas is the number of times a given volume of gas or vapour is as heavy as the same volume of hydrogen at a particular temperature and pressure.
Vapour density = 2 × relative molecular mass of the gas or vapour
Relative molecular mass of SO2 = 32 + 2(16) = 64 
Hence;
Vapour density of SO2 = 64/2
Vapour density of SO2 = 32
 
        
             
        
        
        
The problem can solved using the heat equation which is expressed as:
H = mCΔT
 where H is the energy absorbed or released, m is the mass of the substance, C is the specific heat capacity, and ΔT is the change in temperature.
2208 J = 41 g x 4.18 J/g·°C x ( T - 24 °C) 
T = 36.88 °C