The defects of Mendeleev’s periodic table are:

1. Hydrogen was placed in the group I with alkali metals like Li, Na etc but it could be also placed in the position of halogens.

2. The position of isotopes should be separated .....

The Human Development Index (HDI) is a composite statistic (composite index) of life expectancy, education, and per capita income indicators. HDI is used to rank countries into four tiers of human development. A country scores higher HDI when the .....

A table in which elements is classified into various blocks, periods and group on the basis of their similarities and dissimilarities is called periodic .....

Halogens are called active non-metals because they have 7 valence electron and acquire easiy 1 electron to obtain octet .....

 They are kept separate from other elemnts because of following reasons : They have similar properties with each other but are different from other elements. Their f- subshells is completely .....

The group I A elements are called very active metals because they heave single valence elctrona and donate that electron easily during chemical reaction to form octet .....

The atomic size of potassium is larger than that of sodium. So, the valence electron of potassium can more easily be taken by another reacting atoms as compared to sodium. Hence, sodium is less reactive than .....

Since the atomic size of flourine is smaller than that of chlorine, nuclear attraction is more on the valence shell of the flourine atom. As a result, flourine can get one elctron more easily during the chemical reaction . So, flourine is more .....

In simple words, a share indicates a unit of ownership of a particular company. If you are a shareholder of a company, it implies that you as an investor, hold a percentage of ownership of the issuing company. Shar can be of two types: Equity .....

Chlorine is active non metal because it only has to gain one electron to be in stable .....

The valency of Nitrogen is 3 means that has to gain 3 electrons from the atom to be in stable .....

An atom of argon consists of eight electrons in its outermost orbit. Due to this, it does not take part in chemical reaction. So it is inactive or inert .....

Number of stars in the sky cannot be counted.

Solution: 1 year = 365 days 1 day = 24 hours 1 hour = 60 minutes 1 minute = 60 seconds so, 1 year = 365 *24*60*60 = .....

Meter m is the fundamental unit for the measurement of distance (length) 1 meter mean “the length of the path travelled by light in vacuum during a time interval of 1/299,792,458 of a .....

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1. The units named after scientists are not .....

Chlorophyll is a green pigment present in the leaves of a plant which helps in the absorption of sunlight and also gives the green colour to the .....

General Features All reptiles have a backbone, which means they are vertebrates. All reptiles produce eggs. Most reptiles lay hard-shelled eggs, but a few give birth to live young. All reptiles have scales or scutes. Reptiles are cold-blooded, .....

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In your home, you live with your parents, grandparents, brothers and sisters. You stay with them under one roof. You take care of them. They take care of you. They are your .....

First expression : (a-3)3 = (a-3) (a-3)(a-3) 2nd Expression : a2 - 9 = (a-3) (a+ 3) 3rd expression : a3 + 27 = a3 + 33 = (a+3) (a2 - 3a + 9) So, LCM =  (a-3)(a-3)(a-3) (a+3) (a2 - 3a + 9) = (a+3) (a-3)3 (a2 - 3a .....

Definitely, every society is transforming from primitive to modern because each and everything in the world is changeable. It is a fact that the hunting and gathering societies changed into modern societies in course of time. We know that society .....

Ohm’s Law states that the current flowing through a conductor is directly proportional to the potential difference applied across its ends, provided the temperature and other physical conditions remain unchanged. Mathematically it can be .....

In math, volume can be defined as the 3-dimensional space enclosed by a boundary or occupied by an object. 

Solution : Two euations are : 3x+4y+5 = 0 Slope m1 = -x-coefficient/y-co-efficient = -3/4 Slope m2 = - (x-co-efficient )/ y-coefficient = -6/8  = -3/4 so, slope m1 = slope m2 , thus they are parallel to each .....

The advantages of simple machine are: 1.Simple machines make our work easier by multiplying effort, changing the direction of force or increasing the rate of work.  2. They are simple in structure, easy to handle and require no fuel to .....

By the question, Time(t) = 3 sec By using the formula. h = 1/2gt2 or h = 1/2 ⨉ 10 ⨉ 32 ∴ h = 45 .....

Spring balance is the instrument to measure the weight of the body. and, we know, weight os a variable quantity, so measurement of spring balnace varies from place to .....

1 meter is .....

Solution: Force F = 500N Mass m = 40Kg acceleration a = ? we know, F = m * a or, a = F / m = 500 / 40 = 12.5 .....

There is a deep interrelationship between agriculture, industry and trade. Agriculture provides the raw materials for most industries. These industries produce the goods that are exported to foreign countries. The country earns foreign currencies .....

When sodium bicarbonate is reacted with sulphuric it yields out carbon dioxide. 2NaHCO3 + H2SO4 →Na2SO4 + 2H2O + .....

The fourth summit was held in Islamabad, Pakistan on 29–31 December 1988. Similarly, the twelfth summit was held in Islamabad, on 4–6 January 2004. Pakistan was scheduled to host the 19th  SAARC summit in Islamabad from 15 to 16 .....

Cerebrum is the anterior and largest part of the brain, consisting of two halves or hemispheres and serving to control voluntary movements and .....

Hydrocloric acid is considered to be an inorganic acid because it does not contain carbon and the acid moeity (the proton) is connected .....

Solution : Complementary angle = 90o The complement of 40 = 90 - 40 = .....

प्रश्नले मागेको कुरा प्रष्ट भएन त .....

We can use liquid displacement method to find volume of an irregular bodies. We can use measuring cylinder for finding volume of an irregular .....

Here, Weight(W) = 400N Accleration dur to gravity(g) = 10 ms-2 mass m = ? We know,     W = mg or, 400 = m x 10 or, m = 400 / 10 or, m = 40 .....

A total solar eclipse occurs when the sun is obscured completely by the moon. For a total eclipse to occur, the sun, the moon, and the earth must line up in a straight line. The moon then blocks the sunlight hitting the earth. This results in the .....

A solar eclipse occurs when the moon passes in front of the Sun causing a shadow to fall on certain portions of the Earth. The eclipse is not seen from every place on Earth, but only from the locations where the shadow .....

Soil conservation is the prevention of loss of the top most layer of the soil from erosion or prevention of reduced fertility caused by over usage, acidification, salinization or other chemical soil .....

Viruses show both living and non-living characters. They act as living things when it is in host cell and shows non-living characters when it is outside the living cell. Viruses rely on the cells of other organisms to survive and reproduce, .....

Some of the major differences are:  

Bagmati Province

We know that historical, religious and cultural places are window to the past. The present generation can learn many things from the historical, cultural and religious sites that are handed to us by our ancestors. Some of the things we may learn .....

Derived units are those which depends upon fundmental units. The unit of pressure is N/m2. Since, the Newton is derived unit and metre is fundamental. The unit of pressure is dependent on other units, this is how unit of pressure is derived .....

In Nepal, newar community girls are married thrice but not all the marriage are with men. First girls from newar community marry bel then to Sun and finally with men. The Bel bibaha of Newar girls is called .....

Solution : Tan A = Cot 5A Tan A = Tan ( 90 - 5A) A = 90 - 5A A + 5A = 90 6A = 90 so, A = .....

Menstruation is bleeding from the vagina that happens about once a month, as a normal part of the menstrual cycle. It is also known as having a .....