Questions

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.

Benign prostatic hyperplasia (BPH) also called benign prostatic hypertrophy (or) prostate gland enlargement is a noncancerous enlargement of the prostate gland that can lead to lower urinary tract symptoms (LUTS).

It is the diagnosis characterized by proliferation of the cellular elements of the prostate.

Symptoms ::

As the prostate gets larger, it starts to pinch the urethra. This causes symptoms that affect your urine flow, such as:

* Dribbling when you finish

* A hard time getting started

* A weak stream, or you pee in stops and starts.

Geography is a field of science related to the study of the lands, places, relation between people & their environments. Geography can be understood in terms of five different themes. They are :

• Location
• Place
• Human-Environment Interaction (HEI)
• Movement
• Region.

A gametes are haploid cells as they have only one set of chromosomes. Meiosis is a process of cellular reproduction in which both male and female gametes are formed. During meiosis, the DNA is only replicated or copied one time.

Asterias has bilateral symmetry only at larval stagebut fivefold symmetry (pentamerism, a special type of radial symmetry) as adults.

Nereis do not possess any symmetry elements in their body organisation.

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