1 Revision
Nepal
SEE – Model
Questions 2078
Grade : X F.M.
: 75
Subject: Science
Group-A (15×1=15)
Q.1
Write short answer of the
following questions.
a.
The value of universal Gravitational Constant is
6.67×10-11 Nm2/kg2. What does it mean?
Ans: This means
the force of gravitation between two units of masses keeping/existing at a unit
distance from their centre is 6.67×10-11N.
b.
What is torricellian vacuum?
Ans: The vacuum
which is created at the top of mercury barometer which was invented by
Torricelli mercury barometer which was invented by Torricelli.
c.
Define biomass
Ans: The organic material/substance which can be
converted into energy.
d.
Which metals are used to make nichrome wire? Ans: Chromium
(40%) and nickel (60%).
e.
What is the distance of far point & near point for
normal eye? Ans: Far point is infinity and near point is 25 cm.
f.
Define lanthanides.
Ans: One of the
series of inner-transition elements from number (58-71) after Lanthum is called Lanthanides
g.
What is paraffin?
Ans: The saturated hydrocarbon and another name
for alkanes are paraffin.
h.
Write down the boiling point of aluminum and gold.
Ans: Aluminum = 1800°C Gold = 2610°C
i)
What is saponification?
Ans: The process
by which soap is prepared by the reaction of animals or plants, fat with sodium
hydroxide solution is called saponification.
j)
Define nuptial flight.
Ans: The flight
taken by queen bee to mate with drone bees outside the hive is called nuptial flight.
k)
What is uric acid?
Ans: The
compound formed by carbon, hydrogen, nitrogen and oxygen whose molecular formula is
C5H4N4O3 is uric acid.
l)
What sex chromosomes are found in male and female?
Ans: In male XY and in female XX sex chromosome.
m)
Write the type of sexual reproduction in hydra and
spirogyra. Ans: Hydra-budding, Spirogyra-fragmentation.
n)
What is scion?
Ans: The stem
of a plant which is used in grafting is called Scion or the shoot system of a
plant that is used for grafting.
o)
What is geological time scale?
Ans: A time
scale that includes the earth’s history from its origin to the present is called geological time scale.
Group-B (13×2=26)
Q.2
Write down the two conditions in which the body
becomes weightless. Ans: Two conditions for weightlessness:
i)
The body should fall freely only under the influence
of the force of gravity.
ii)
If the body is at the earth’s center or in the space at null point (g=0)
Q.3
Study the given figure and answer the
following.
wt. f stone in
liquid= 7 N wt. of liquid displaced = 2N
i)
What is the actual weight of the stone?
Ans: Actual weight is weight in
air
i.e. Wa = Weight in Water + Weight of displaced liquid
= 7N + 2N
= 9N
ii)
State the principle in which this experiment is based on?
Ans: The given arrangement works on Archimedes principle which states
that, "An object fully or partially submerged into a liquid experiences
the upthrust equal to the weight of water displaced by it."
Q.4
Energy crisis may occur in the world in near future.
"Justify this statement with two reason."
Ans: i) Due to overpopulation, urbanization &
industrialization, the demand of sources of energy are increasing in alarming rate.
iii) 80% energy are obtaining from non-renewable sources.
Q.5
An electric heater draws a current of 10A from 220V
supply. What is the cost of electricity using that a heater for 7 hours per day
in a month? The rate of unit cost is Rs.10.
Ans: Given,
Current drawing
(I) = 10A Potential difference (P.d.) = 220V For a heater,
No. of heater (n) = 1 Time (T) = 7 hr/day Power (P) = I×V
= 10×220
= 2200W
= 2200/1000 KW
= 2.2 KW
Now,
Electrical energy consumed in one
day = n×p×T
= 1×2.2×7
= 15.4 KW/hr
= 15.4 unit Cost per unit (R) = Rs.10
Cost for one day
= Rs.10×15.4 = Rs.154 Cost for one month = 30×154 = Rs.4620
Q.6
Which one is more reactive in between fluorine and chlorine, why?
Ans: Fluorine
is more reactive in between fluorine and chlorine because fluorine has small
atomic size and hence more electronegativity which helps to attract the electron more easily than chlorine.
Q.7
Write
the structural formula of glycerol and write any one use of acetylene. Ans: Structural formula of gycerol is,
Use of acetylene
– used in the production of polyethylene plastics or other matched answer.
Q.8
State any two causes of chemical pollution.
Ans: i) Production
of basic metals
ii)
motor vehicles
iii)
textile industry
iv)
production of rubber
Q.9
Two chemical substances A and B when mixed at room
temperature react very slowly. Suggest two different ways of increasing the
rate of this reaction.
Ans: i) by
increasing the temperature
ii) by supplying the more atmospheric pressure.
Q.10
Write the one-one function of given hormones
i)
parathormone ii) progesterone
Ans: i) parathormone
= maintains the calcium level in blood
ii)
progesterone = maintenance of pregnancy
Q.11
Write any two points to show the economic importance of silkworm.
Ans: i) by selling the silk obtained from
silkworm, we can level up the economic
status.
ii) We can get employment opportunity
Q.12
During blood donation, blood is drawn from the vein
but not from the artery, why?
Ans: The walls
of veins are thinner than arteries. The blood pressure in veins is less than
that in arteries. Veins are closer to the surface of skin which make easier by
avoiding deep needle plunge just to draw a bit of blood.
Q.13
Write any two differences between male gamete and
female gamete. Ans:
|
Male gamete |
Female Gamete |
|
i) sperm cell |
i) egg cells |
|
ii) produced by male reproductive organs |
ii) produced by female reproductive organs |
Q.14
The tail of a comet disappears as it moves away from the sun, why?
Ans: The tail
of a comet is formed when it reaches nearer to the sun by getting radiation and
get evaporates dust gas. So if it moves away from sun it does not get radiation
and its tail disappears.
Group-C
(6×8=18)
Q.15
The weight of a person on planet ‘A’ is 580N. What
will be his weight on the planet ‘B’ whose mass is 6 times and radius is 2
times than that of planet ‘A’?
Ans: Weight of
a person on planet ‘A’ (W1) = 580N Mass
of the 1st planet = M
Radius of the
1st planet = R the weight of the person is,
F1= GMm/R2
580= GMm/R2 (i)
Weight of a
person on planet ‘B’ (W2) = ? Mass of 2nd planet (M2)= 6M
Radius of 2nd
planet(R2)=4R Weight of theperson(F2)=GM2m/R22
=G.6Mm/(2R)2
=6/4 x (GMm/R2)
=1.5 x 580 [from eqn—- i]
= 870N
Q.16
Answer the following question on the basis of the given table.
|
Substances |
Specific heat capacity |
|
A |
470 J/kg°C |
|
B |
910 J/kg°C |
|
C |
380 J/kg°C |
a)
The sp. heat capacity of substance ‘C’ is 380 J/kg’C, what does it mean?
Ans: This means 380J heat energy is required to raise the temperature of
1kg substance C by 1’C.
b)
If equal heat is given to equal masses, which one will
have the highest temperature, why?
Ans: Substance C will have highest temperature as it has the lowest
specific heat capacity.
c)
Which substance will penetrate to the greatest depth
if each with equal mass are put on a wax-slab after heating to 100’C each, why?
Ans: Substance B will penetrate the deepest as it has highest value of S
nd it will be hotter for longest period.
Q.17
A compound given Ca+ ion and OH– ion when
dissolved in water.
i)
What happens when this compound reacts with ammonium
salt on heating? Write with chemical equation.
Ans:
The compound is calcium hydroxide Ca(OH)2. Ammonia gas is formed.
2NH4Cl + Ca(OH)2 CaCl2 + 2NH3 + H2O
Salt and water will be formed
ii)
Write one use of this compound.
Ans: To reduce the hyperacidity
of stomach, it is used
iii)
What
happens when this compound is reacted with hydrochloric acid? Ans: 2HCl + Ca(OH)2 CaCl2 +
2H2O
Q.18
Which glass is formed if the mixture of silica,
potassium carbonate and lead monoxide is heated. Write its one special property
and two uses.
Ans: Lead
crystal glass is formed. It has high refractive index.
Uses
i)
To make lenses, prisms, electric bulbs.
ii)
To make TV & radar tubes.
Q.19
What is tissue culture? How it is done? Write any two
importance of vegetative propagation.
Ans: Tissue culture is modern technique of vegetative propagation. With
the help of culture solution, it is done.
Importances of vegetative
propagation,
i)
it is cheap & rapid method relative to a long period of seed dormancy.
ii)
The plants which do not produce viable seeds can be
easily propagated by this method.
eg. banana, rose etc.
Q.20
Write any three adverse effects caused by soil pollution.
Ans: Adverse effects caused by soil pollution, are
i)
affects the plants as well as any other forms of life negatively.
ii)
degrades the quality of soil such as texture, water
holding capacity, porosity etc.
iii)
Kill various useful animal living inside the soil.
Group-D
(4×4=16)
Q.21
i) What is the defect of vision of the eye
in the given figure?
Myopia.
ii) Write the causes of this defect (any two).
Ans: Elongation of eye ball,
decreasing the focal length of eye lens etc.
iv)
How can we correct this defect?
Ans:)By using the concave lens of
suitable focal length.
v)
Draw the diagram for its remedy. Ans:
Q.22
i)
Which gas is collected in gas jar?
ii)
What is Y in given figure? Why is it
used?
i)
How is urea prepared from this gas? Write with chemical equation.
Ans: i) Ammonia gas
ii)
Y is lime tower.
Lime tower
(CaO) is used to absorb the water which is in moisture from during the chemical
reaction produced along with ammonia gas.
iii)
Urea is prepared when ammonia gas reacts with carbon
dioxide gas under pressure and
temperature at about 1500°C.
Chemical
equation
2NH3 + CO2
1500°C
NH2–CO–NH2 + H2O.
Q.23
Draw
a chart showing the crossing between tall and dwarf pea plants till F2
generation. Find out the genotypic and phenotypic ratio of F2 generation. When
the mating of black and white rats takes place all the off spring produced in
first generation are black, why?
Here, Phenotypic
ratio in F2-generation Tall: Dwarf= 3:1
Genotypic ratio = pure tall:
hybrid tall: pure dwarf= 1:2:1
When the mating
of black and white rets takes place all the off spring produced in first
generation are black because among black & white colour, black is dominant
over white and according to law of dominance only one characters is seen is
first generation.
Q.24
Draw a neat diagram to show the different layers of
atmosphere and write the adverse
effects of ozone layer depletion.
Ans:
The effects of ozone layer
depletion are as follows,
a. damage to DNA and leads to mutation
b. damage to skin cells
c. ageing of skin
d. cause various types of cancers
e. cataract