Chemistry Questions

Adenosine triphosphate (ATP) is a nucleotide which is also called as nucleoside triphosphate is a small molecule used in cells as a coenzyme. It is often referred to as the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism. Most of the cellular functions need energy in order to be carried out such as synthesis of proteins, synthesis of membranes, movement of the cell, cellular division, transport of various solutes etc. The ATP is the molecule that carries energy to the place where the energy is needed. When ATP breaks into ADP (adenosine diphosphate) and P_i (phosphate), the breakdown of the last covalent link of phosphate liberates energy that is used in reactions where it is needed.

The stability of the ions is determined by the energy of the lone pairs. Carbon has the least effective nuclear charge (Zeff) and so the lone pair on the CH3− ion has the highest energy, making it the least stable ion and so the strongest base. The Zeff increases as we move across the period until we get to fluorine which has the greatest Zeff and so its lone pairs have the lowest energy, making F− the least basic ion.

In order of decreasing basicity they are ranked LiCH3 > LiNH2 > LiOH > LiF. We are dealing with the ions F−, OH−, NH2− and CH3− and so the factor which influences their basicity is the stability of the ion compared to its conjugate acid.

In a chemical reaction, substances (elements or compounds) called reactants are changed into other substances (compounds or elements) called products. Hence, reactants are those which start the chemical reaction.

For example:

1. In the burning of natural gas, methane (CH4) and oxygen (O2) are the reactants in the chemical reaction. are the substances formed by a chemical reaction. In the burning of natural gas, carbon dioxide (CO2) and water (H2O) are the products formed by the reaction.

2. H2+O2 ----> H2O

Here H2 & O2 are called Reactants and H2O is called Product.

Mixtures are combination of two or more substances physically which can be separated in to the original.

Matter can be breakdown into two categories. 

1) Pure substances 

2) Mixtures

Here in the given options, options A, B, C are pure substances as they are indicated as S & L in brackets. Option D) is an aqueous solution, that can be dissolved in water.