Balbharti Maharashtra State Board Class 9 Geography Solutions Chapter 6 Properties of Sea Water Notes, Textbook Exercise Important Questions and Answers.

Class 9 Geography Chapter 6 Properties of Sea Water Textbook Questions and Answers

1. Tick the correct box according to the salinity of the ocean water ✓

Answer:
(a) Low
(b) Low
(c) High
(d) High
(e) Low
(f) High.

2. Give reasons.

(a) Salinity is low in the land-locked Baltic Sea.
Answer:

(b) There is higher salinity in the northern Red Sea while lower in the southern.
Answer:

(c) Oceans located at the same latitude do not have same salinity.
Answer:

(d) With increasing depth, the temperature of sea water decreases to a certain limit.
Answer:
With increasing depth, the temperature of sea water decreases to a certain limit because –

(e) There are more salt-pans on the Western coast of India than its eastern coast.
Answer:

(f) Salinity increases in the mid-latitudinal zones.
Answer:

3. Answer the following questions.

(a) What are the factors affecting the salinity of the sea water?
Answer:

(b) Explain the distribution of salinity around the Tropic of Cancer and tropic of Capricorn.
Answer:

(c) What are the factors affecting the temperature of the sea water?
Answer:

(d) Explain the changes occurring in the temperature of sea water according to the depth.
Answer:

(e) Name the factors affecting salinity.
Answer:
Due to the sun’s heat, evaporation happens at a faster rate. Evaporated water turns into water vapour and reduces in quantity. But amount of salt remains the same in the remaining water and therefore the salinity of water increases.

4. Explain how temperature affects the following.

(a) the density of sea water
Answer:

(b) the salinity of sea water
Answer:

Activity:

Complete the table showing the salinity of open and land-locked seas.

Answer:

Class 9 Geography Chapter 6 Properties of Sea Water Intext Questions and Answers

Observe the following Map and answer the questions:

Question 1.
What is the salinity around the tropics?
Answer:
The salinity around the tropics is 36%o.

Question 2.
Which region has the least salinity?
Answer:
The Bay of Bengal has the least salinity of 32%o.

Question 3.
Which ocean has salinity more than 37%o?
Answer:
Atlantic ocean has salinity of more than 37%o.

Question 4.
What are the reasons of differences in salinity on a global level?
Answer:
The uneven distribution of temperature on earth, and uneven supply of freshwater, etc. are the reasons for differences in salinity on a global level.

Observe the Graph and answer the questions:

Question 1.
What is the maximum temperature of seawater in equatorial areas? How much is this temperature at a depth of 500 m?
Answer:
The maximum temperature of sea water in equatorial areas is 18° C. The temperature at the depth of 500 m is 11° C.

Question 2.
What is the temperature of seawater at the sea level in the mid-latitudes?
Answer:
The temperature of seawater at the sea level in the mid-latitudes is 14° C approximately.

Question 3.
How much has this temperature changed at 1500 m depth?
Answer:
The temperature is about 5° C at the depth of 1500 m. Thus the temperature of sea water at mid-latitudes has changed from 14°C at the sea level to about 5°C at the depth of 1500 m i.e. temperature has changed (reduced) by 9°C.

Question 4.
What does the thermal graph for the high latitude say? What is its temperature at 500, 1000 and 1500 m depths?
Answer:
In high latitudes the temperature of sea water at all depths remains constant at 4° C.

Question 5.
After what depth does the seawater temperature remain stable everywhere?
Answer:
After 2000 m, the temperature of the sea water is uniform everywhere.

Question 6.
With increasing depth, what decreases: temperature, salinity or density?
Answer:
Temperature and salinity decreases with increasing depth.

Question 7.
After what depth does the change in these factor become almost zero?
Answer:
After the depth of 1000 m there is no change in all these factors.

Question 8.
Till what depth is the change in these factors higher?
Answer:
The higher change can be seen up to a depth of about 500m.

Question 9.
Explain the correlation between all the three factors.
Answer:
If the temperature is less, density is more. If the salinity is less, then density is also less. However temperature affects the density more as compared to the salinity. If the temperature is less, then the density is more despite less salinity.

Let’s Recall.

Question 1.
Which is the largest water storage of the world?
Answer:
Oceans are the largest water storage of the world.

Question 2.
Why is the seawater salty?
Answer:

Question 3.
What are the reasons for high salinity in the oceans?
Answer:
High rate of evaporation and low supply of fresh water leads to high salinity in the oceans:

Question 4.
How can we obtain the salts from the ocean water?
Answer:

Question 5.
What is the use of the salts in the oceans to us?
Answer:

Can You Tell?

Question 1.
What is the difference in the temperatures of the land and the sea?
Answer:
During the daytime land is hotter than the sea whereas, during the night time land is cooler than the sea.

Question 2.
What would be the difference in the temperature of the seawater from the equatorial region to the polar areas?
Answer:
Latitudinally, the surface temperature of the seawater decreases from the equatorial areas towards the poles. The average temperature in equatorial areas is around 25° C while it is about 2° C near the poles.

Think about it.

Question 1.
If you think about India there is the Arabian sea to the west and the Bay of Bengal to the east. The salinity of the eastern coast is 34%o while it is 35%o in the Arabian sea. What could be the reason of higher salinity in the western coastal region?
Answer:
Many large peninsular rivers drain their waters in the Bay of Bengal and on the contrary only small seasonal coastal rivers drain in the Arabian sea. Hence the salinity of Arabian sea is more than the Bay of Bengal.

Try this.

Question 1.
In which container has the water increased or decreased?
Answer:

Question 2.
What could be the reasons behind the decrease or increase?
Answer:

Question 3.
What could be the reason behind the low and high salinity of the water in the container?
Answer:

Class 9 Geography Chapter 6 Properties of Sea Water Additional Important Questions and Answers

Select the correct option:

Question 1.
The average temperature in equatorial areas is
(a) 25° C
(b) 35° C
(c) 15° C
(d) 5° C
Answer:
(a) 25°C

Question 2.
The average temperature in mid-latitudes is
(a) 25° C
(b) 10° C
(c) 16° C
(d) 5° C
Answer:
(c) 16°C

Question 3.
The average temperature near poles is about
(a) 10° C
(b) 20° C
(c) 15° C
(d) 2° C
Answer:
(d) 2°C

Question 4.
With the increasing depth of sea, the intensity of sunrays
(a) increases
(b) decreases
(c) remains constant
(d) is uneven
Answer:
(b) decreases

Question 5.
Seawater upto the depth of 500m is called
(a) ground water
(b) surface water
(c) deep water
(d) saline water
Answer:
(b) surface water

Question 6.
ocean is the most saline ocean in the world.
(a) Pacific
(b) Arctic
(c) Indian
(d) Atlantic
Answer:
(d) Atlantic

Question 7.
The sea lying on the border of Israel and Jordan has a salinity of %o.
(a) 37
(b) 50
(c) 256
(d) 332
Answer:
(d) 332

Question 8.
The buoyancy of the sea water increases because of its
(a) evaporation
(b) salinity
(c) density
(d) high temperature
Answer:
(b) salinity

Question 9.
has an altitude of – 400m.
(a) Baltic Sea
(b) Arabian Sea
(c) Dead Sea
(d) the Mediterranean Sea
Answer:
(c) Dead sea

Question 10.
act as temperature controllers at a global level.
(a) Ocean currents
(b) Sea breeze
(c) Land breeze
(d) Trade winds
Answer:
(a) Ocean currents

Question 11.
is a major porperty of the sea water.
(a) Temperature
(b) Uniform salinity
(c) Buoyancy
(d) Equal Density
Answer:
(a) Temperature

Question 12.
have higher salinity than open seas.
(a) Equatorial seas
(b) Landlocked seas
(c) Freshwater lakes
(d) Seas in polar regions
Answer:
(b) landlocked seas

Question 13.
Temperature decreases upto depth.
(a) 500 m
(b) 1000 m
(c) 1500 m
(d) 2000 m
Answer:
(d) 2000m

Question 14.
In regions where cold currents flow, the surface temperature of ocean water is
(a) high
(b) less
(c) uniform
(d) uneven
Answer:
(b) less

Question 15.
Temperature of seawater changes rapidly with depth in areas.
(a) equatorial
(b) mid latitudinal
(c) temperate
(d) polar
Answer:
(a) equatorial

Question 16.
In seas where the rate of evaporation is than the supply of fresh water, salinity is high.
(a) less
(b) high
(c) same
(d) low
Answer:
(b) high

Question 17.
The salinity of Bay of Bengal is than that of Arabian sea.
(a) less
(b) more
(c) same
(d) equal
Answer:
(a) less

Question 18.
In areas the salinity of sea water is low.
(a) equatorial
(b) mid-latitudinal
(c) temperate
(d) polar
Answer:
(d) polar

Question 19.
The salinity of Battic sea is %.
(a) 332
(b) 32
(c) 37
(d) 7
Answer:
(d) 7

Match the Column:

Column A	Column B
(1) Equatorial areas (2) Mid-latitudinal areas (3) Temperate regions	(a) Salinity of 332%o (b) Slanting sunrays, melting of snow (c) Cloudy sky and convectional rainfall (d) Hot deserts

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Answer:
(1-c),
(2- d),
(3 – b)

Answer in one sentence:

Question 1.
What is the major property of seawater?
Answer:
Temperature is a major property of seawater.

Question 2.
What is the average surface temperature of seawater in equatorial areas, mid-latitudes & poles?
Answer:
The average surface temperature of seawater is equatorial areas is around 25°C in mid-latitude it is around 16°C & 2°C near the poles.

Question 3.
After what depth is the seawater temperature uniform everywhere?
Answer:
After 2000m, the temperature of seawater is uniform everywhere

Question 4.
Name the instruments used to measure salinity?
Answer:
Hydrometer, Refractometer and salinometer are used to measure salinity.

Question 5.
Which is the most saline ocean?
Answer:
The Atlantic ocean is the most saline ocean.

Give geographical reasons:

Question 1.
The climate of the earth gets affected by ocean currents.
Answer:

Question 2.
Dead Sea has a salinity of 332%0.
Answer:

Question 3.
The surface temperature of the sea is not uniform everywhere.
Answer:

Question 4.
The seas in equatorial calm belt are more saline.
Answer:

Explain

Question 1.
Factors affecting surface water temperature
Answer:

Question 2.
Density of sea water
Answer:

Question 3.
Measurement of salinity of sea water.
Answer:

Question 4.
Factors affecting salinity of sea water.
Answer:

Latitudes	Temperature / Rate of evaporation	Supply of fresh water	Salinity
Tropical Zone 5°N – 5°Sof equator	High	Abundant from (River Congo / Amazon)	High
Mid­latitudes (25° – 35° N and S)	High (hot desert are found here)	low	High
Temperate regions	Temperature is lower due to slanting sunrays	The supply of water is more due to melting snow	low
Polar regions	Very low	low	low

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