All solutions here are SUGGESTED. Mr. Teng will hold no liability for any errors. Comments are entirely personal opinions.

(i)
Order a numbered list of 100,000 employees. Using a random number generator, randomly select 90 numbers from 1 to 100,000 and select that employee to survey.

It will not be representative as it will not be evenly spread.

(ii)
Use stratified sampling.
Sample by proportions based on the countries the employees are based in. For example, if China has 5000 employees, we will sample $\frac{10000}{100000} \times 90 = 9$ people from there. Perform simple random sampling to obtain the names of those surveyed.