GATE Questions

---

The law of conservation of mass states that in any closed system the mass of the system is neither created nor destroyed over time i.e, the mass cannot be changed overtime.

Hence, the given statement is true.

Polarity :: 

The polarity of a molecule defines its other physical properties such as melting point, boiling point, surface tension, vapor pressure etc... Simply, polarity occurs when the electron distribution in a molecule is asymmetric. This results in a net dipole moment in the molecule. One end of the molecule is charged negative while the other gets a positive charge.

The polarization of a molecule greatly depends on the shape of the molecule. A diatomic molecule like HF mentioned above has no issue of shape. The net dipole moment is only due to the uneven distribution of electrons between the two atoms. However, when there are more than two atoms involved in making a bond, there are many complexities.

The water molecule is of bent shape. Therefore, when the two pair of electrons shared by oxygen with two hydrogen atoms is pulled towards oxygen, the net dipole moment results in the direction of the oxygen atom. There is no other force to cancel out the resultant dipole moment. Hence, the water molecule is highly polar.

Ammonia molecule is of a pyramid shape and the electronegative N atom pulls the electrons towards itself. The three N-H bonds are not in the same plane; hence the dipole moments created do not get canceled out. This makes ammonia a polar molecule.

However, the dipole moments sometimes get canceled due to the shape of the molecules, making the molecule non-polar. Carbon dioxide is such a molecule.

Any properties that are dependent on the amount of matter are called as extensive properties of matter.

Examples are :: Mass, Volume, Density (M/V),...

The Mirror can turn everything around without moving.

Zoroastrianism is one of the world's oldest extant religions. It is the ancient pre-Islamic religion of Iran that survives there in isolated areas and, more prosperously, in India, where the descendants of Zoroastrian Iranian (Persian) immigrants are known as Parsis, or Parsees.

The Iranian prophet and religious reformer Zarathustra flourished before the 6th century BCE more widely known outside Iran as Zoroaster is traditionally regarded as the founder of the religion.

Zoroastrianism contains both monotheistic and dualistic features. It likely influenced the other major Western religions—Judaism, Christianity, and Islam.