Imagine an atom made p of proton and a hypothetical particle of double the mass of the electron but having he same charge as the electron. Apply the Bohratom model and consider all posible transitions of this hypothetical particle to the first excited level. The longest waveength photon that will be emitted has wavelength λ (given in terms of the Rydberg constant R for the hydrogen atom) equal to:
Which of the following substances is/are ozone depleting? Select the correct answer from the codes given below:
(1) Chlorofluorocarbons
(2) Halons
(3) Carbon tetrachloride
Sodium metal crystallizes in a body centred cubic lattice with a unit cell edge of 4.29 Å. The radius of sodium atom is approximately :
The most malleable metal is:
Which of the following is the best criteria of purity of organic compounds?
The luster of a metal is due to:
The number of hydrogen atom(s) attached to phosphorus atom in hypophosphorous acid is:
The octane number of zero is assigned to:
Which of the statements given below is/are correct?
Permanent hardness of water is due to the presence of soluble.
(1) Chloride of calcium
(2) Bicarbonate of calcium
(3) Sulphate of magnesium
(4) Bicarbonate of magnesium
Select the correct answer using the codes given below.
Consider the following statements : (i) Washing soda on strong heating gives sodium oxide and carbon dioxide.
(ii) Plaster of Paris is obtained by heating gypsum at 373 K.
(iii) Bleaching powder is used for disinfecting drinking water.
Which of these statement(s) is/are correct ?
Tertiary alkyl halides are practically inert to substitution by SN2 mechanism because of:
The term anomers of glucose refers to:
Consider the following statements and select the correct code.
Assertion (A): The main constituent of the
liquefied petroleum gas is methane.
Reason (R): Methane can be used directly for burning in homes and factories where it can be supplied through pipelines.
Which among the following elemtns are generally find in free state?
What happened when a hard boiled egg after shelling is immersed in saturated brine?
Which among the following are constituents of Brass?
For a spontaneous change in a system at constant temperature and pressure, which of the following statements is true?
What is the magnitude of the restoring force exerted when an elastomer chain is extended by 25% at 25°C? Assume that the length of each bond within the elastomer backbone is 154 pm.
In which among the following categories, Radon (Rn) can be placed?
(1) Radioactive Element
(2) Inert Gas
(3) Noble Gas
Choose the correct option:
Due to rusting the weight of iron:
The law which states that the amount of gas dissolved in a liquid is proportional to its partial pressure is:
The heat energy produced when the human body metabolises 1 gram of fat is:
To which orbitals may an electron in a 2p orbital in a hydrogenic atom make allowed spectroscopic transitions?
Which of the following copper alloys is used for the manufacture of springs and suspension filaments in electrical instruments?
Which one has the highest boiling point?
Atomic number of an element gives
Group 0 elements are ____________.
Density of a 2.05 M solution of acetic acid in water is 1.02 g/mL. The molality of the solution is:
Hubble’s law is based on the:
Natural rubber is a polymer derived from ?