Questions

The main causes for the boat accidents are ::

1. Excessive speed

2. Machinery failure

3. Operator inexperience

4. Alcohol use

5. Operator inattention

6. Lack of proper look-out

7. Careless/reckless behavior and hull failure

8. Hazardous waters

and some more...

The United Arab Emirates (UAE) central bank (UAECB) and the Saudi Arabian Monetary Authority (SAMA) have announced that the interbank digital currency they are co-developing will be called 'Aber.'

All India Radio founded in 1930.

With over 420 radio stations in about 23 languages & 179 dialects.

AIR is one of the largest radio broadcasters in world.

It also has 99.19% population coverage & 18 FM channels.

The Aortic valve - located between the left ventricle and the aorta

The Mitral valve - located between the left atrium and left ventricle

The Tricuspid valve - located between the right atrium and the right ventricle (and) 

The Pulmonary (pulmonic) valve - located between the right ventricle and the pulmonary artery.

Atoms are composed of three main particles called electrons, protons and neutrons. We know that, the electrons are negatively charged particles whereas protons are positively charged and neutrons have no charge.

Hence, as the number of electrons and protons are equal and they are oppositely charged, the atom will have no charge as their charges cancel each other.

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.