faila ala Flashcards
Give two practical applications of reflection of sound waves.
The phenomenon of sound reflection occurs when a traveling sound wave hits an obstruction causing it to return in a different direction.
The angle of incidence of the sound wave is always equal to the angle of reflection of the sound wave.
The phenomenon of echo occurs due to the reflection of sound
what are the major group of activities involved for improving of crop yields
Crop variety improvement [1 Mark]
Crop production improvement [1 Mark]
Crop protection management [1 Mark]
. Is it not proper to regard the gaseous state of ammonia as vapours ? Explain
Gaseous state of a substance is regarded as vapours only if it is a liquid at room temp. ammonia is a gas at room temp. so it cannot be regarded as vapours.
What is Malleability
Malleability means that metals can be hammered into sheets and foils. For example, aluminium foils are used for wrapping food stuffs, silver foils are used for decorative purposes on sweets and fruits. Ductility means that metals can be drawn into wires. Gold and silver wires are used in ornaments.
How does fungi and bacteria can withstand much greater changes in the surrounding medium than animal cells?
Fungi and bacteria have cell walls, which allow them to survive extremely diluted external media without bursting. By osmosis, the cells absorb water, expand, and create pressure against the cell wall.
Describe the role played by the lysosomes. Why are these termed as suicidal bags?
If the cell gets damaged, then one of the lysosomes bursts, releasing those digestive enzymes. The released enzymes then digest their own cell and ultimately the cell dies.
What are characteristic structural features of meristematic cells?
The meristematic tissue has the quality of self-renewal. Every time the cell divides, one cell remains identical to the parent cell, and the others form specialized structures. They have very small and few vacuoles. The meristematic tissue is living and thin-walled.
Why is the motion in a circle at constant speed called accelerated motion?
The motion of a body which is moving with constant speed in a circular path is said to be accelerated because its velocity changes continuously due to the continuous change in the direction of motion.
Distinguish between work, energy and power. State the SI units for each of these quantities.
Work
Energy
Power
Work is said to be done on a body when it moves through a certain distance under the effect of the force applied to it.
SI unit of work is joules (J).
It depends upon displacement.
Energy can be defined as the capacity or ability to do work.
SI unit of energy is joules (J).
It does not depend upon displacement or time.
Power can be defined as work done per unit of time.
SI unit of power is watt (W).
It depends upon time.
what is a closed system
only the exchange of energy is allowed but the exchange of matter is not allowed. Example-When we boil water with a closed lid, the heat can exchange but matter cannot.
State the law of conservation of energy
the amount of energy is neither created nor destroyed
How moths of certain families are able to escape captures from bats? What is the range of frequencies associated with : (a) infrasound? (b) ultrasound?
They have very sensitive hearing equipment, can hear the squeaks (ultrasound) of bat and know when a bat is flying nearby. (a) Less than 20 Hz. (b) More than 20,000 Hz.
Write down the difference between isotopes and isobars.
Isotopes are atoms with the same number of protons but differing numbers of neutrons. Isobars are atoms of different chemical elements having equal values for atomic mass. Isotopes have the same atomic number. Isobars have different atomic numbers.
An element 12X24 loses two electrons to form a cation which combines with the anion of element 17Y35 formed by gaining an electron. (i) Write the electronic configuration of element X. (ii) Write the electronic configuration of the anion of element Y. (iii) Write the formula for the compound formed by combination of X and Y.
a) X = 2,8,2
b) Y = 2,8,7
c) XY2
Explanation:
since X has 12 as it’s atomic no. and 24 as it’s mass then :-
atomic no. = no. of electrons = no. of protons
so, electronic configuration ( according to Bohr’s model) (2,8,8,18….)
X = 2,8,2 ( 2+8+2 = 12)
valency of X is +2
similiarly for Y . 17 = atomic no. and 35 is it’s atomic mass;-
no. of electrons = no. of protons = 17
so electron configuration will be :- 2,8,7 ( 2+8+7 = 17)
valency of Y is -1
c) so formula will be
X Y
+2 -1
XY2
Explain the structure of a nervous tissue with details about its location and function.
nerve tissue is the main tissue of our nervous system. It monitors and regulates the functions of the body. Nervous tissue consists of two cells: nerve cells or neurons and glial cells, which helps transmit nerve impulses and also provides nutrients to neurons.
