lesson number 14 elements compounds and mixtures fill in the blanks
Answers
Answer:
Question 1:
Who are my companions ?
Group 'A' Group 'B'
1. Stainless steel (a) Non-metal
2. Silver (b) compound
3. Bhajini mixture (c) Mixture
for milling
4. Salt (d) Element
5. Coal (e) Alloy
6. Hydrogen (f) Metal
ANSWER:
Group 'A' Group 'B'
1. Stainless steel (e) Alloy
2. Silver (f) Metal
3. Bhajini mixture (c) Mixture
for milling
4. Salt (b) compound
5. Coal (a) Non-metal
6. Hydrogen (d) Element
Page No 99:
Question 2:
Write the names of elements from the following symbols :
Zn , Cd, Xe, Br, Ti, Cu, Fe, Si, Ir, Pt.
ANSWER:
Zn- Zinc
Cd- Cadmium
Xe- Xenon
Br- Barium
Ti- Titanium
Cu- Copper
Fe- Iron
Si- Silicon
Ir- Iridium
Pt- Platinum
Page No 99:
Question 3:
What are the molecular formulae of the following compounds ?
Hydrochloric acid, sulphuric acid, sodium chloride , glucose, methane.
ANSWER:
Hydrochloric acid- HCl
Sulphuric acid- H2SO4
Sodium chloride- NaCl
Glucose- C6H12O6
Methane- CH4
Page No 99:
Question 4:
Give scientific reasons.
(a) Buttermilk is churned to get butter .
(b) In chromatography, the ingredients of a mixture rise up to a limited height water rises up to upper end of the paper .
(c) A wet cloth is wrapped around a water storage container in summer .
ANSWER:
a. Butter milk has two components- water and fat/cream. Churning helps in the separation of these two components. The fat/cream collects on the top as a result of churning while the remaining part is left behind as liquid.
b. Chromatography is a separation technique used to separate the different components in a liquid mixture. Separation of substances by chromatography is based on two properties of the substance:
solubility of the substance in the solvent that moves up
ability of the substance to stick to the stationary filter paper
These properties are different for different substances and are mutuall opposite to each other. It is the reason why all the components of the mixture rise upto a limited height when water rises up to the upper end of the paper.
c. A wet cloth is wrapped around water containers in summers to keep the container and the water inside it cools. The water present in the cloth evapourates and along with that water the heat also evapourates thus keeping the container and water cool.
Page No
Atoms
Molecules
(i)
Atoms are the smallest particles of an element that can take part in a chemical reaction.
(i)
Molecules are the smallest parts of an element or compound, which exist independently.
(ii)
They do not break up during chemical reactions.
(ii)
They break up during chemical reactions.
(iii)
They may or may not exist in free state.
Explanation:
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