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Name three groups of plants that bear archegonia. Briefly describe the life cycle of any one of them.

Three groups of plants that bear archegonia are given below: Bryophytes Pteridophytes Gymnosperms. The life cycle of a pteridophyte, then it consists of two morphologically distinct phases: (i) The gametophytic phase (ii) The sporophytic phase. These two phases come one after another in the life cycle of a pteridophyte and this phenomenon is called alternation of generation. The gametophyte...

Give me a easy answer 

Law of gravitation applies on each planet and it also applies on earth towards the moon but the motion or acceleration of earth towards the moon is very slow and it goes unnoticed. 

Q2. What shape is (a) Your instrument box? (b) A brick? (c) A matchbox? (d) A road-roller? (e) A sweet laddu?

the shape of the following things are (a) Your instrument box- Cuboid (b) A brick- Cuboid (c) A matchbox-Cuboid (d) A road-roller- Cylinder (e) A sweet laddu-Sphere

Find (i)\frac{7}{9}-\frac{2}{5} \ \ \ \ \ (ii) 2 \frac{1}{5}-\frac{(-1)}{3}

1:-  0.5

2:-  2.5

What will be the additive inverse of \frac{-3}{9} ?, \frac{-9}{11} ?, \frac{5}{7} ?$

The additive inverse of   The additive inverse of  The additive inverse of  

What is binary number

A binary number is represened by 0 and 1. The binary number system has base 2. It is used in digital electronics. For example 7 can be represented in binary system as 111. That is 

Nios board

NIOS is National Institute of Open Schooling and is the board under the Union Government of India.  

Calculate the molar mass of the following substances. (c) baking soda



Why is glass considered a super cooled liquid?

Glass is an amorphous solid. Just like liquids, amorphous solids also have a tendency to flow, though very slowly. Therefore, these are called pseudo solids or supercooled liquids.

During sunrise and sunset, the light has to travel a long distance in the atmosphere. So light of small wavelength scatters and the least scattered light reaches our eyes. Red is the least scattered light. So sky looks red.

The following are the reasons for using steel instead of other materials to make robots. 

1. Steel is commonly available and it is found in the form of an alloy of Iron.

2. It is stronger than other metals like aluminum.

3. Welding is easy to do 

4. It blunts tools easily.

Hence the above reasons make steel favorable building material for Robots.


The material selected for making robot depends on the application. Wood, plastics, aluminium, steel, ceramics etc are used to make a robot. 

How many stars in milky way?



3.20 b) Given the resistances of 1 Ω, 2 Ω, 3 Ω, how will be combine them to get an equivalent resistance of (iii) 6 Ω

Attach them in series

Question 6. Let ∗ be the binary operation on N given by a ∗ b = L.C.M. of a and b. Find

(v) Which elements of N are invertible for the operation ∗?


HOF is an oxidizing agent which is extremely unstable and it is highly reactive and corrosive in nature. It is used as the explosive material because it is highly unstable due to the high electronegativity difference between fluorine and hydrogen and due to its property of breaking down into HF and O2   

Reaction showing breakdown of HOF 

2 HOF → 2 HF + O2

What is displacement and distance

Distance:- “how much ground an object has covered” during its motion. It is a scalar quantity.   Displacement:- how far out of place is an object. It is the shortest distance between two points. It is a vector quantity. Example:- If a particle is moving in a circular motion. After the first cycle of its motion, the distance covered by this particle is   (r is the radius of the circle. But the...
Here is the solution:

     Write these in ascending and also in descending order.

              (a)  \frac{1}{8},\frac{5}{8},\frac{3}{8}

             (b)  \frac{1}{5},\frac{11}{5},\frac{4}{5},\frac{3}{5},\frac{7}{5}

            (c)  \frac{1}{7},\frac{3}{7},\frac{13}{7},\frac{11}{7},\frac{7}{7}

option A

     Which is the larger fraction?

              (i)  \frac{7}{10} or \frac{8}{10}

              (ii)  \frac{11}{24} or \frac{13}{24}

             (iii)  \frac{17}{102} or \frac{12}{102}

The fractions are shown below using greater than or less than sign                      (i)                           (ii)                         (iii)