Physics , Science-Technology Test 1
The inert gas which is substituted for nitrogen in the air, used by deep sea
drivers for breathing, is
Explanation: Helium is used as a substitute for nitrogen in breathing mixtures for deep-sea divers. This is because helium is less soluble in the bloodstream and reduces the risk of nitrogen narcosis, a condition that can affect divers at great depths.
Amalgams are
Explanation: Amalgams are alloys that contain mercury. They are commonly used in dental fillings, where mercury is combined with metals like silver, tin, or copper to form a durable material.
Actinides are the elements with atomic numbers from
Explanation: The actinides are the series of elements with atomic numbers from 89 (actinium) to 103 (lawrencium). These elements are typically radioactive and include uranium, thorium, and plutonium, among others.
Human body needs a constant supply of proteins to survive. The first part
of the digestive system to begin digesting proteins is
Explanation: The stomach is the first part of the digestive system where protein digestion begins. It secretes gastric juices containing pepsin, an enzyme that breaks down proteins into smaller peptides, and hydrochloric acid, which creates an acidic environment to aid enzyme activity.
The average salinity of sea water is
Explanation: The average salinity of seawater is about 35 parts per thousand (‰), which means 35 grams of dissolved salts per kilogram of seawater. This is equivalent to 3.5%.
Which one of the following is used for dating archaeological specimens in
words, bones and shells?
Explanation: Carbon-14 dating, also known as radiocarbon dating, is commonly used to determine the age of archaeological specimens such as wood, bones, and shells. This method is based on the radioactive decay of the carbon-14 isotope.
Chemical formula for water glass is