Posts

Showing posts from January, 2021

The above reaction is an example of a: (a) combination reaction. (b) double displacement reaction. (c) decomposition reaction. (d) displacement reaction.

-
Image
Ques 2: The above reaction is an example of a:              Fe 2  O 3  + 2 Al → Al 2   O 3  + 2 Fe (a) combination reaction. (b) double displacement reaction. (c) decomposition reaction. (d) displacement reaction. Ans 2: (d) The given reaction is an example of a displacement reaction.                                                             
Post a Comment
Read more

Which of the statements about the reaction below are incorrect?

-
Image
Ques 1: Which of the statements about the reaction below are incorrect?              2 P b O + C → 2 P b + CO (a) Lead is getting reduced. (b) Carbon dioxide is getting oxidised. (c) Carbon is getting oxidised. (d) Lead oxide is getting reduced. (i) (a) and (b) (i i) (a) and (c) (i i i) (a), (b) and (c) (i v) all Ans 1: (i) (a) and (b)                                                                                                          
Post a Comment
Read more

Conservation of momentum in a collision between particles can be understood from

-
Ques : Conservation of momentum in a collision between particles/bodies can be understood from (a) Conservation of energy (b) Newton’s second law only (c) Newton’s first law only (d) Both Newton’s second and third law Ans : (d) Both Newton’s second and third law If there is no external force acting on a system (called isolated) of constant mass, the total  momentum of the system remains constant(no change) with time. For a two system of particles in absence of any external force by law of conservation of linear  momentum. Important point: We should not confuse with the system and the individual particles. As total external force on the system of both particles is zero but force acts on individual particles.  Law of conservation of linear momentum is independent of frame of reference(ground level or at some height) while linear momentum depends on frame of reference. 
Post a Comment
Read more

What are the environmental consequences of using the fossil fuels? Suggest some steps to minimise the pollution caused by various sources of energy including non-conventional sources of energy.

-
Ques: What are the environmental consequences of using the fossil fuels? Suggest some steps to minimise the pollution caused by various sources of energy including non-conventional sources of energy.  Ans: Environmental consequences of using fossil fuels are: (i) They are the largest emitters of greenhouse gases such as sulphur dioxide, carbon dioxide and methane. (ii) Extraction of conventional fuels threatens the ecological balance in some areas. (iii) These fuels can cause environmental problems due to pollution. Steps to minimize the pollution are : (i) The dependency on fossil fuels should be reduced by switching to any other sources of energy. (ii) The judicious use of energy by avoiding the wastage can reduce environmental problems.  (iii) Regular servicing of energy conversion devices should be done in order to maintain their efficiency. Unit 14 (Sources of Energy) (iv) We should focus on developing the technology that should make the energy conversion devices much mo...
Post a Comment
Read more

Write two different ways of harnessing energy from ocean.

-
Ques: Write two different ways of harnessing energy from ocean. Ans: Tidal energy and Ocean thermal energy  can be harnessed from ocean.
Post a Comment
Read more

Why is there a need to harness non-conventional sources of energy? Give two main reasons

-
Ans:  There is a need to harness the non-conventional sources of energy because: (i) fossil fuels are present in limited amount and are depleting fast. (ii) burning of fossil fuels causes a lot of air pollution.
Post a Comment
Read more

Identify the compound X on the basis of the reactions given below. Also, write the name and chemical formulae of A, B and C.

-
Image
Ques: Identify the compound X on the basis of the reactions given below. Also, write the name and chemical formulae of A, B and C. Ans: 
Post a Comment
Read more

Match the important chemicals given in Column (A) with the chemical formulae given in Column (B).

-
Image
Ques: Match the important chemicals given in Column (A) with the chemical formulae given in Column (B). Ans: 
Post a Comment
Read more

A student prepared solutions of (i) an acid and (ii) a base in two separate beakers. She forgot to label the solutions and litmus paper is not available in the laboratory. Since, both the solutions are colourless, how will she distinguish between the two?

-
Ques: A student prepared the solutions of (i) an acid and (ii) a base in two different beakers. She forgot to label the solutions and litmus paper is not available in the laboratory. Since, both the solutions are colourless, how will she distinguish between the two of them? Ans: Add phenolphthalein (which is a indicator) to a portion of each solution in separate test tube. If it turns pink, then, the beaker contains base whereas if it remains colourless, it's an acid. If phenolphthalein is not available, pH paper can also be used. Acid will turn pH paper red, base will turn pH paper blue.
Post a Comment
Read more

What happens when nitric acid is added to egg-shell?

-
Ans: Egg-shell is made up of calcium carbonate( Ca CO 3) which will react with  HNO 3  to form  C 2 (g) and  H 2 (l) along with calcium nitrate.  Ca CO 3  +   HNO 3  →   Ca( NO 3 ) 2 +   CO 2   +   H 2 O
Post a Comment
Read more

Name the acid present in ant sting and give its chemical formula. Also give the common method to get relief from the discomfort caused by the ant sting.

-
Ans: Ant sting contains methanoic acid (HCOOH) (formic acid). Its chemical formula is HCOOH. The common method to get relief from it is to apply paste of (baking soda) on it.
Post a Comment
Read more

What will be the action of the following substances on litmus paper? Dry.HCl gas, Moistened NH3 gas, Lemon juice, Carbonated soft drink, Curd, Soap solution.

-
Ans: Dry HCl(hydrochloric acid) gas will have no effect on litmus paper. Moistened  NH 3  gas will turn red litmus blue. Curd, carbonated soft drink, lemon juice will turn blue litmus red. Soap solution will turn red litmus blue.
Post a Comment
Read more

Match the acids given in Column (A) with their correct source given in Column (B).

-
Image
Ques: Match the acids given in Column (A) with their correct source given in Column (B). Ans.(a) —> (iv)         (b) —> (iii)          (c) —> (ii)          (d) —> (i) Lactic acid is present in curd,milk,etc. ; acetic acid is generally present in vinegar, citric acid is present in orange, lemon and oxalic acid is generally present in tomato.
Post a Comment
Read more

NCERT Solutions class 10 Science Chapter 9 || (Heredity and Evolution Solution Class 10 Science Chapter 9 || Heredity and Evolution Solution || Biology || Science ||

-
Image
Ques 1: A Mendelian experiment consisted of breeding tall pea(matar) plants bearing violet flowers with short pea plants bearing white flowers. The progeny of all bore violet flowers, but almost half  of them were short. This suggests that the genetic make-up of the tall parent can be depicted as   (a) TTWW (b) TTww (c) TtWW (d) TtWw Ans 1: (c) The genetical make-up of the tall parent can be depicted as TtWW .  Since all the progeny of pea plant bore violet flowers, it means that all the tall plants are having violet flowers has W W genotype for violet flower colour.   Since the progeny is both tall tall and short, the parent plant was not a pure tall plant. Its genotype must be T t.   Therefore, the cross involved in the given in the question is                        TtWw × ttww                            ...
Post a Comment
Read more

Find out the following in the electric circuit given below in the figure:

-
Image
Ques: Find out the following in the electric circuit given in figure: (a) Effective resistance of two 8 Ω resistors in the combination, (b) Current flowing through 4 Ω resistor, (c) Potential difference across 4 Ω resistance, (d) Power dissipated in 4 Ω resistor,  (e) Difference in ammeter readings, if any. Ans: (a) Effective resistance, the two 8 Ω resistors in parallel, R = 8×8 / 8+8    = 4 (b) equivalent resistance = 4 + R = 8 Ω So, current through 4 Ω = I = V/R = 8/8 = 1A   (c) Potential difference = V = IR = 1×4 = 8 V (d) Potential dissipated = I²R = I² × 4 = 4 V (e) No difference, since the ammeters are connected in series and the same amount if current pass through them, so the reading of both the ammeters will be same. 
Post a Comment
Read more

Popular posts from this blog

QUANTUM NUMBERS (Principal, Azimuthal, Magnetic and Spin)

-
Image
                  QUANTUM NUMBERS  Orbitals represent regions in the space around the nucleus where the probability of finding the electron is maximum. A large number of electron orbitals are possible in atom. These can be distinguished by their size, shape and orientation of the orbitals. To describe each electron in an atom in different orbitals, we need a set of three numbers known as quantum numbers. These are designated as n, l and m. In addition to these three numbers another quantum number is also needed which specifies the spin of the electron. These four numbers are called quantum numbers. These are discussed below: 1. Principal quantum number (n) :  This quantum number determines the main energy shell or level in which the electron is present. It is denoted by n. It can have whole number values starting from 1 such as n = 1, 2, 3, 4 ... This quantum number also identifies as shell. The shell with n 1 is called the first sh...
Read more

Diagonal Relationship between Beryllium and Aluminium || Relation between Beryllium and Aluminium

-
  Diagonal Relationship between Beryllium and Aluminium The ionic radius of Beryllium (Be 2+) is estimated to be nearly 31 pm; the charge/radius ratio Or e/m ratio is nearly the same as that of the Al 3+ ion. Hence beryllium resembles aluminium in these ways. Some of the similarities are given below: » Like Aluminium, Beryllium(be) is not readily attacked by acids H+ donor because of the formation of an oxide film on the surface of the metal by reacting with oxygen, i.e. they are rendered passive by nitric acid. » Beryllium hydroxide[[Be(OH)4]2] dissolves in excess of alkali to give a beryllate ion, [ Be(OH)4]2– just as aluminium hydroxide[Al(OH)3] gives aluminate ion, [Al(OH)4] » The chlorides of metals beryllium and aluminium have Cl– bridged chloride structure in vapour phase. Both the chlorides are soluble in organic solvents and are strong as Lewis acids They are used as Friedel Craft catalysts. » Beryllium(Be) and aluminium(Al) ions have strong tendency to form complexes, (Be...
Read more

Math question

-
Image
A tower, x metre, has a flagstaff at its top. The tower and flagstaff subtends equal angles at a point distant y metre from the foot of the tower. Then find the length of the flagstaff ( in metre). 
Read more

Solar System, Planets, Moons, Asteroid Belt,Kuiper Belt and Oort Cloud, Comets and Meteoroids

-
Image
 The solar system consists of the Sun, which is a star at its center, and all the celestial bodies bound by its gravitational pull. These bodies include planets, moons, asteroids, comets, and other objects. Key Components of the Solar System: The Sun : The Sun is the center of the solar system and contains about 99.86% of its mass. It is a star primarily composed of hydrogen and helium, providing the heat and light that sustains life on Earth. Planets : There are eight recognized planets in the solar system: Mercury : The closest planet to the Sun, known for extreme temperature variations and no atmosphere. Venus : Similar in size to Earth but with a thick, toxic atmosphere and surface temperatures hot enough to melt lead. Earth : The third planet from the Sun, the only known planet to support life, with water and a breathable atmosphere. Mars : Known as the Red Planet, it has a cold, dry surface and signs of past water. Jupiter : The largest planet, a gas giant, w...
Read more