Science

Question 1

Acid spills on student’s hands what do you do

Answer 1

Wash hands with plenty of water and apply a paste of sodium hydrogen carbonate

Question 2

why does the sun appear red during sunset

Answer 2

scattering of light

Question 3

what processes are involved in making a rainbow

Answer 3

internal reflection, dispersion, refraction

Question 4

the noon the sun is white because

Answer 4

light is least scattered at noon

Question 5

Hg metal

Answer 5

Mercury

Question 6

what happens when copper is corroded

Answer 6

4Cu + O2 = 2Cu2O

Question 7

What are the materials used to make steel

Answer 7

Fe, Cr (chromium), Ni (nickel)

Question 8

Corrosion of silver reaction

Answer 8

Ag2O + H2S → Ag2S + H2O

Question 9

properties of ionic compounds

Answer 9

1. solid and hard
2. high melting and boiling points
3. soluble in water
4. conduct electricity in liquid form
   NOT in solid

Question 10

Which mirror is a rear-view mirror

Answer 10

convex mirror

Question 11

what is obtained when iron is subjected to steam

Answer 11

Fe3O4

Question 12

light travels fastest in

Answer 12

vacuum>air>water>glass>diamond

Question 13

ability to be drawn into wires

Answer 13

ductility

Question 14

ability to be drawn into sheets

Answer 14

malleability

Question 15

Lead Nitrate + Potassium Iodide

Answer 15

Pb(NO3)2 + 2KI → PbI2 + 2KNO3

yellow ppt

Question 16

lipase acts upon

Answer 16

fats

Question 17

lead nitrate is heated, reaction

Answer 17

2Pb(NO3)2→2PbO+4NO2+O2

Question 18

Zn + NaOH

Answer 18

Zn + 2NaOH → Na2ZnO2 + H2

Question 19

lime water formula

Answer 19

Ca(OH)

Question 20

salts that contain water of crystallization are

Answer 20

gypsum, blue vitriol, epsom salt, Glauber’s salt

Question 21

phenolphthalein in acid and base

Answer 21

base - pink

acid - colourless

Question 22

non metallic oxides nature

Answer 22

acidic

Question 23

bleaching powder formula

Answer 23

also called chlorine CaOCl2