Answer: A) H and Br Explanation: Only H and Br form Polar Covalent Bond.   Covalent bonding: Covalent bonding occurs when pairs of electrons are shared by atoms. Atoms will covalently bond with other atoms in order to gain more stability, which is gained by forming a full electron shell. By sharing their outer most (valence) electrons, atoms can fill up their outer electron shell and gain stability. 1. Polar Covalent Bond 2. Nonpolar Covalent Bond   1. Polar Covalent Bond: A Polar Covalent Bond is created when the shared electrons between atoms are not equally shared. This occurs when one atom has a higher electronegativity than the atom it is sharing with. The atom with the higher electronegativity will have a stronger pull for electrons (Similiar to a Tug-O-War game, whoever is stronger usually wins). As a result, the shared electrons will be closer to the atom with the higher electronegativity, making it unequally shared.   2. Nonpolar Covalent Bond: A Nonpolar Covalent Bond is created when atoms share their electrons equally. This usually occurs when two atoms have similar or the same electron affinity. The closer the values of their electron affinity, the stronger the attraction. This occurs in gas molecules; also known as diatomic elements. Nonpolar covalent bonds have a similar concept as polar covalent bonds; the atom with the higher electronegativity will draw away the electron from the weaker one.   Here H and H and N and N form Non-polar covalent bonds. Na and Br form the ionic bond.

Answer: A) C2H6O Explanation: C2H6O is a Non-electrolyte.   An electrolyte is a compound that conducts an electric current when it is in an aqueous solution or melted. In order to conduct a current, a substance must contain mobile ions that can move from one electrode to the other. All ionic compounds are electrolytes. When ionic compounds dissolve, they break apart into ions which are then able to conduct a current ( conductivity ). Even insoluble ionic compounds such as CaCO 3 are electrolytes because they can conduct a current in the molten (melted) state.   A nonelectrolyte is a compound that does not conduct an electric current in either aqueous solution or in the molten state. Many molecular compounds, such as sugar or ethanol, are nonelectrolytes. When these compounds dissolve in water, they do not produce ions.   Electrolytes are of 3 types ---- Strong Electrolytes, Weak Electrolytes and Non Electrolytes.   Strong Electrolytes ---- Compounds which completely dissolves. ( NaCl, Na2Co3, HCl ) Weak Electrolytes ----- Compounds which do not completely dissolves. Non Electrolytes ------ Compounds which do not dissolves at all.

Answer: D) Rs. 960 Explanation: Let C.P. = Rs. C. Then, 832 - C = C - 4482C = 1280 => C = 640Required S.P. = 150% of Rs. 640 = 150/100 x 640 = Rs. 960.

Answer: C) Temperature Explanation: The land breeze is a coastal breeze at night blowing from the land to the ocean. It is caused by the difference in the rates of cooling of the land and of the ocean. Once again, the bigger the difference in temperature between the two, the stronger the wind.

Answer: D) Bhagirathi Explanation: Tehri dam is located on the river Bhagirathi. It is a multi-purpose rock and earth-fill embankment dam on the Bhagirathi River near Tehri in Uttarakhand, India.   It is the primary dam of the THDC India Ltd. and the Tehri hydroelectric complex.

An Egg is more useful when it is broken than it is not.

A Coin has a Head and tail but no body. Since the two sides of coin are called as heads and tails.

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.