Top 10 chemistry factsChemistry quiz
Why were photographic prints sepia toned?
For improved resistance. Sepia toning enhances archival qualities of the photos. Chemicals are used to convert the metallic silver in the print to a sulfide compound, which is at least 50% more stable than silver.
What is the active component of pepper spray?
Capsaicin. Pepper spray (also known as capsicum spray) is a chemical compound that irritates the eyes to cause tears, pain, and temporary blindness used in policing, riot control, crowd control, and self-defence.
What was included in the original Pepsi-Cola recipe?
Digestive enzyme. Pepsi Cola, first introduced in 1898, was named after pepsin (enzyme) and kola (nuts). In 1931, the company entered bankruptcy and changed hands. The new owners changed the recipe to resemble more Coca-Cola.
What is the effect of nicotinic acid on human organism?
It is essential for functioning. Nicotinic acid, better known as niacin or vitamin B3, has nothing in common with tobacco. Chronic lack of niacin leads to pellagra, a vitamin deficiency disease.
What is the only physical difference between heavy water and pure water?
Heavy water has greater density. Heavy water contains deuterium instead of common hydrogen-1. In its pure form it has a density about 11% greater than water, but otherwise, it is physically and chemically similar. It is not radioactive. Because of greater density and stronger hydrogen-oxygen bonds, its behaviour is slightly different in some biochemical reactions. It may be toxic, but only when a large fraction of water (> 50%) in higher organisms is replaced by heavy water.
What is the strongest known acid?
Fluoroantimonic acid is an ionic liquid created by reacting hydrogen fluoride with antimony pentafluoride in stoichiometrically equivalent amounts. The 1:1 combination forms the strongest known superacid, 10^16 (10 quadrillion) times stronger than 100% sulfuric acid.
What is the densest substance in the universe?
Neutron star. A neutron star is a stellar remnant of a supernova. Neutron stars are very small, but extremely dense - with a radius of only about 12–13 km (7 mi), they can have a mass of about two Suns.
Why do elements erbium, yttrium, ytterbium, terbium, have similar names?
From the name of the Swedish Ytterby mine. Ytterby mine, located in the south-east part of the Swedish island and the town Resarö, was a rich source of many rare minerals. 4 chemical elements - yttrium, ytterbium, terbium and erbium - were named after the mine commemorating their origin.
What substance has the lowest value of LD50 (median lethal dose)?
Botox. The value of LD50 for a substance is the dose required to kill half the members of a tested population after a specified test duration. Botox is the most acutely lethal toxin known, with an estimated human LD50 of 1.3–2.1 ng/kg intravenously or intramuscularly and 10–13 ng/kg when inhaled.
Does the candle burn more or less violently in zero gravity?
Less violently. In zero gravity, no convection occurs, that normally shapes the flame, disperses CO2 and brings fresh air to the wick. Without convection, CO2 from combustion does not disperse as readily and tends to smother the flame