Questions

The number of bonds between a pair of atoms is called the bond order.

Bond orders can be calculated from Lewis structures, which are the heart of the valence-bond model. Oxygen, for example, has a bond order of two.

When there is more than one Lewis structure for a molecule, the bond order is an average of these structures. The bond order in sulfur dioxide, for example, is 1.5  the average of an S-O single bond in one Lewis structure and an S=O double bond in the other.

In molecular orbital theory, we calculate bond orders by assuming that two electrons in a bonding molecular orbital contribute one net bond and that two electrons in an antibonding molecular orbital cancel the effect of one bond. We can calculate the bond order in the O₂ molecule by noting that there are eight valence electrons in bonding molecular orbitals and four valence electrons in antibonding molecular orbitals in the electron configuration of this molecule. Thus, the bond order is two.

In chemistry, a metal is an element that readily forms positive ions (cations) and has metallic bonds. Metals are opaque, lustrous elements that are good conductors of heat and electricity. Most metals are malleable and ductile and are, in general, denser than the other elemental substances.

Examples of metals are aluminium, copper, iron, tin, gold, lead, silver, titanium, uranium, and zinc.

Here Se - Selenium is an element but is not a metal, S - Sulphur is not a metal and I - Iodine is also not a metal.

Hence, Zn - Zinc is the only metal in the given options.

Kandla is Tidal port, Kolkata Haldia is  a  riverine  port,  Tuticorin  is  a river  port,  Marmagao  is  in  Goa,  is situated   on   estuary   on   eastern coast of India. Delta formation and estuary    formation    take    place mostly  on  western  coast  and  Goa is in western coast. 

Zakir Hussain is best known for the instrument Tabla.

Bundu Khan is known for Sarangi

P. Mani Iyer is known for Mridangam

Ravi Sankar is known for Sitar

DRAM is a Volatile random-access memory (VRAM).

Volatile random-access memory (VRAM) is random-access memory that retains its information when power is turned on.

Examples of volatile memory are primary storage (typically dynamic RAM, DRAM), and fast CPU cache memory (typically static RAM, SRAM, which is fast but energy-consuming and offer lower memory capacity per area unit than DRAM).

Non-volatile random-access memory (NVRAM) is random-access memory that retains its information when power is turned off.

Examples of non-volatile memory are flash memory (used as secondary memory) and ROM, PROM, EPROM and EEPROM memory (used for storing firmware such as BIOS).