# Tutor profile: Divya N.

## Questions

### Subject: Chemistry

In an reduction reaction, about 0.380 grams of sodium borohydride was used. What is the amount in mmol used of this compound?

Step 1: Figure out the formula of sodium borohydride, which is NaBH4 Step 2: Figure the molecular weight (g/mol) of NaBH4: Mass of Na is 22.989 g/mol , B is 10.811 g/mol , and H is 1.008 g/mol (1 x 22.989)+(1 x 10.811)+(4 x 1.008)= 37.832 g/mol of NaBH4 Step 3: Use stoichiometry to convert g to mmol of NaBH4 (0.380 g of NaBH4) x (1 mol of NaBH4/ 37.832 g of NaBH4) x (1000 mmol/1 mol)= 10.04440685 mmol of NaBH4 Step 4: The answer should be rounded off according to the rules of significant figure. The maximum amount of significant figure would be three since 0.380 g has a significant figure of three. Answer: 10.0 mmol of NaBH4 was used.

### Subject: Basic Chemistry

What is the center of an atom called? Also, what does the center of an atom contain?

The center of an atom is called the nucleus and it contains protons and neutrons.

### Subject: Algebra

Solve for x in ((1/4)x)-(1/2(x))=1

Step 1.) The denominator of the fraction needs to be the same. Thus, the fraction -((1/2)(x)) is multiplied by two ((1/4)x)-(2/4(x))=1 Step 2.) Combine the two fractions ((1x-2x)/4)=1 (-x/4)=1 Step 3.) Multiply four on both sides in order to get rid of the denominator. Then you get this: -x=4 Step 4.) In order to solve for x divide -1 on both sides x=-4