●
Red litmus paper is changed into blue in solution of which thing? Base
● Blue litmus paper is converted into red in solution of which thing? acid
● What is the substance which decreases the rate of a chemical reaction? Poison
● Which gas has maximum colorific value? Oil gas
● In which type of coal percentage of carbon is the highest? Anthracite
● What is the mixture of carbon monoxide and nitrogen called? Producer gas
● What is the mixture of carbon monoxide and hydrogen called? Water gas
● Which fuel causes minimum environmental pollution? Hydrogen
● Which gas has the highest fuel value? Hydrogen
● Which hydrocarbon is mainly present in gobar gas? Methane
● What happens when the door of a refrigerator is kept open? Room heated
● Which is the element having lowest melting point in periodic table? He
● Which transition metal is in liquid state?
Mercury,
● By whom was the calculation of electronegativities first done? Pauling,
● Which element does not exist in liquid state at room temperature ? Na
● What is the most electropositive amongst the alkaline earth metals? Barium
● Which are the vertical lines in modern periodic table called? Group
● Which noble gas does not have octet of electrons in its outer shell? He
● Which pair of elements is in the same period of the periodic table? Na, Cl
● What is the Electron affinity of noble gases?
Almost zero
● Which mirror is to be used to obtain a parallel beam of light from a small
lamp ?Concave mirror
● Which is used to remove astigmatism for a human eye? Cylindrical lens
● Why does diffusion of light in the atmosphere take place? Due to dust particles,
● Total internal reflection can take place when light travels from which thing?
Diamond to glass,
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