The main use of litmus is to test whether a solution is acidic or basic. Light-blue litmus paper turns red under acidic conditions, and red litmus paper turns blue under basic or alkaline conditions, with the color change occurring over the pH range 4.5–8.3 at 25 °C (77 °F). Neutral litmus paper is purple.

Methyl Iodide, 99%  used for alkylating carbon, oxygen, sulfur, nitrogen and phosphorus nucleophiles. ... In the Monsanto process, the in situ formed iodomethane reacts with carbon monoxide in the presence of a rhodium complex to give acetyl iodide, which on hydrolysis yields acetic acid.

1. The upper opening of the funnel A (Fig. 15) should be the same size as that of tube F, so that the funnel may be used as a receiver in the distillation described below (Note 12).

Malachite green has classically been used by the light microscopist for the demonstration of fungi and bacterial spores. It is a weakly basic diaminotri- phenylmethane dye with useful indicator properties at both very high and very low pH     Malachite Green is used for bacterial spore staining by Schaeffer and Fulton`s method. It can also be used in place of methyl green in the Pappenheim stain, when combined with the Gram stain.

It is used as a nutritional supplement and for the treatment of hypoprothrombinemia. Menadione is a member of the class of 1,4-naphthoquinones that is 1,4-naphthoquinone which is substituted at position 2 by a methyl group. 

Mercury is also used in dental fillings, paints, soaps, batteries, and fluorescent lighting. 

Mercury will dissolve numerous metals to form amalgams and is used to extract gold dust from rocks by dissolving the gold and then boiling off the mercury

Methane sulphonic acid is an alkanesulphonic acid and its chemical formula is CH3SO3H. ... Therefore MSA is considered as green acid. Therefore its use in organic synthesis attracts many chemists to use in organic synthesis. In this review we described the MSA catalyzed organic transformation.

Methanesulfonic acid (MSA) is a strong organic acid. ... It is considered a green acid as it is less toxic and corrosive in comparison to mineral acids

Molybdenum occurs naturally in various ores, the most important being molybdenite (MoS2), 

which is converted to molybdenum trioxide (MoO3) for use

in ferro- and manganese alloys, chemicals, catalysts, ceramics, and pigments.

Further, Mo–O connection appeared to exhibit both ionic (the charge transfer from 2p orbital of oxygen to molybdenum) and the covalent (charge accumulation in the region of Mo–O) components

N,N,N′,N′-tetramethyl-p-phenylenediamine dihydrochloride (TMPD) is an oxidizable compound that serves as a reducing co-substrate for heme peroxidases. It is also used as a test reagent in microbiology for the classification of cytochrome oxidase positive aerobic microorganisms.

Thymol blue (thymolsulfonephthalein) is a brownish-green or reddish-brown crystalline powder that is used as a pH indicator. It is insoluble in water but soluble in alcohol and dilute alkali solutions.        Thymol blue is used as a pH indicator. It transitions from red to yellow at pH 1.2–2.8 and from yellow to blue at pH 8.0–9.6. It is usually a component of Universal indicator (1).

N-bromosuccinimide (NBS) is used as a highly specific bromination agent both in free-radical 

substitutions and in electrophilic additions of unsaturated systems, because releases small quantities of bromine.

NBS is used as a substitute for Br2 in these cases since Br2 tends to react with double bonds to form dibromides. The advantage of NBS is that it provides a low-level concentration of Br2, and bromination of the double bond doesn't compete as much.