Question

1. Isopropyl alcohol (rubbing alcohol) has a density of 0.8218 g/ml at 25 ˚C. What is the volume in ml of I kg of isopropyl alcohol at 25˚C? SHOW WORK PLEASE

2. True or False: Protons and electrons have opposite charges of the same magnitude, while

electrons have a much smaller mass compared to protons.

3. Of the following pairs of elements, which pair would have the most similar properties? Why?

a)B & Be

b)O & Cl

c)Cs & F

d)Br & Kr

e)Li & K

4. How many moles of Al do 13.49 grams of Al represent? SHOW WORK PLEASE

5. Complete and balance each of the following chemical reactions.

      a)                  Mg      +          Br₂   

      b)                  Li         +          F₂   

      c)                  CH₄     +          O₂   

Answer 1

Ans:

1. Density of Isopropyl alcohol (rubbing alcohol) = 0.8218 g/ml at 25 ˚C.

So volume in ml of I kg of isopropyl alcohol at 25˚C

d = m/v or v=m/d = 1Kg/0.8218 =   1.216841 Liter

2.      Protons and electrons have opposite charges of the same magnitude, while electrons have a much smaller     mass compared to protons. True

3. Pair of elements having similar properties.

e)         Li & K . Both li and K belong to the same group and have ns¹ electron in valance shell.

4. Moles of Al do 13.49 grams of Al represent?

Atomic weight of Al= 26.98.

Mole = weight taken/ Atomic weight of the element. So moles of al= 13.49/26.98 =0.50 mole.

5. Chemical reactions.

a)                 Mg      +          Br₂ -> Mg Br₂

b)                2 Li         +          F₂ -> 2LiF   

c)                CH₄     +         2 O₂ -> CO₂+ 2H₂O