Question

List any four social media services that help you to keep in touch with your family and friends.

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Answer 1

1. WHATSAPP

2. INSTAGRAM

3. FACEBOOK MESSENGER

4. SKYPE

Answer 2

(a) 6.023 x 10 23 atoms of oxygen has mass = 16 g

So, 1 atom has mass = 16/6.023 x 1023 = 2.656 x 10-23 g

(b) 1 atom of Hydrogen has mass = 1/6.023 x 1023 = 1.666 x 10-24

(c) 1 molecule of NH3 has mass = 17/6.023 x1023 = 2.82 x 10-23 g

(d) 1 atom of silver has mass = 108/6.023 x 1023 =1.701 x 10-22

(e) 1 molecule of O2 has mass = 32/6.023 x 1023 = 5.314 x 10-23 g

(f) 0.25 gram atom of calcium has mass = 0.25 x 40 = 10g