10 self study question with answer--13

Question 1

What are the elements present in urea ______?

  C,H,O

  C,N,O

  C,N,H

  C,O,N,H

It's 'C,O,N,H '
Urea is an organic compound with the chemical formula CO(NH₂)₂. The molecule has two —NH₂ groups joined by a carbonyl (C=O) functional group.

Question 2

The most abundant element in the universe is __________.

  Hydrogen

  Oxygen

  Carbon dioxide

  Silicon

It's 'Hydrogen '
Hydrogen is more abundant than any other element, making up about 3/4the mass of the universe. . Helium is second, making up almost all of the remaining 25%. Oxygen is a distant third.

Question 3

The substance which increases the rate of chemical reaction is __________.

  Metal

  Catalyst

  Alloy

  Enzymes

It's 'Catalyst '
The substance which increases the rate of chemical reaction is called catalyst. With a catalyst, reactions occur faster and require less activation energy.

Question 4

pH is an abbreviation for?

  Power of Hydrogen

  Possibility of Hydrogen

  Population of Hydrogen

  Position of Hydrogen

It's 'Power of Hydrogen '
pH is an abbreviation for Power of hydrogen. The concentration of hydrogen ions is commonly expressed in terms of the pH scale. A pH less than 7represents an acidic solution and a value higher than 7 is basic or alkaline.

Question 5

German silver is an alloy of _______?

  copper, nickel and silver

  silver, copper and aluminium

  zinc, copper and nickel

  silver, zinc and copper

It's 'zinc, copper and nickel '
German silver is a copper alloy with nickel and often zinc. The usual formulation is 60% copper, 20% nickel and 20% zinc.

Question 6

__________ are biological catalysts.

  Enzymes

  Minerals

  Proteins

  Vitamins

It's 'Enzymes '
Enzymes are biological molecules (proteins) that act as catalysts and help complex reactions occur everywhere in life.

Question 7

The most abundant constituent in Air is __________.

  Oxygen

  Hydrogen

  Carbondioxide

  Nitrogen

It's 'Nitrogen '
Nitrogen is a chemical element with symbol N and atomic number 7. On Earth, the element forms about 78% of Earth's atmosphere and as such is themost abundant uncombined element.

Question 8

Isotopes are atoms of the same element with different numbers of __________.

  Protons

  Electrons

  Neutrons

  Positron

It's 'Neutrons '
Isotopes are variants of a particular chemical element which differ in neutron number, although all isotopes of a given element have the same number of protons in each atom.

Question 9

A radioactive substance emits ______?

  alpha particle

  beta particle

  gamma particle

  all of the three

It's 'all of the three '
Radioactive substances are continually producing three kinds of dangerous radiation: alpha particles, beta particles and gamma rays. These types of radiation are invisible to the naked eye, and so you won't see a green glow.

Question 10

Bronze is an alloy of ________.

  Gold and Zinc

  Copper and tin

  Tin and Zinc

  Iron and Zinc

It's 'Copper and tin '
Bronze is an alloy consisting primarily of copper and other metals. The addition of other metals produces an alloy much harder than plain copper.