Which of the following is 2.45986 rounded to 3 significant
digits?

The rounded three digits for the given number is 2.46

Explanation:

Significant figures are the number of digits in a value which contributes to the degree of accuracy of the value while measuring

Rules:

Digits which are not zero are always essential. Any zeros between two major digits are important. Only a final zero or trailing zeros are important in the decimal section

Solution:

Given number-  2.45986Decimals- 5 digitsScientific Notation -2.45986 × 10^0Applying the rules until rounding the 3 digits we get,The rounded three digits for the given number is 2.46

For cyclohexane compounds drawn in a chair conformation:   -axial bonds are vertical  -equatorial bonds are parallel to two bonds within the ring.  thus, as i assume the chair conformation is drawn:   -the x group is in an axial position, as are the five other vertical bonds.  -three axial bonds are on the top face of the ring  -the other three axial bonds are on the bottom face  the position of the second substituent on each ring carbon is equatorial.  gauche groups must be on an adjacent carbon such as carbon 6 and carbon 2, and also gauche groups are rotated by 60 degrees relative to each other.  drawing the newman projections for c1–c2 and c1–c6 aids in visualizing the groups that are gauche to the y group on c1.  click this link and watch some academic videos that may you more understand the topic