CBSE 11TH CHEMISTRY - Online Test
Q1. Among the alkali metals the most abundant are:
Answer : Option B
Explaination / Solution:
Na and K are highly abundant. Constituting 2.5 and 2.4 percent of the Earth's crust respectively the othwe alkali metals are considerably rare.
Q2. Which of the following organic compound Wohler synthesised from an inorganic compound, ammonium cyanate in the presence of heat:
Answer : Option B
Explaination / Solution:
The reaction can be given as starting with solutions of potassium cyanate and ammonium chloride which are mixed, heated and cooled again to get ammonium cyanate salt which on decomposition gives the urea.
Q3. According to Gay Lussac’s Law of Gaseous Volumes,
" when gases combine or are produced in a chemical reaction they do so in a ______ ratio by volumes provided all gases are at same temperature and pressure."
Answer : Option A
Explaination / Solution:
Gay lussac’s law states that when gases combine or are produced in a chemical reaction they do so in a simple ratio by volume provided all gases are at same temperature and pressure.
Mathematically , the law is expressed as ,
[ V / n ] = k
where V represents volume of the gas , n denotes number of moles of the gas & k is proportionality constant .
Thus, volume ratio must be related to the relative number of molecules.
This relationship was crucial in establishing the formula of simple molecules at a time when a distinction between atoms and molecules was not clearly understood.
Q4. Avogadro law states that
Answer : Option B
Explaination / Solution:
Equal volumes of all gases under the same conditions of temperature and pressure contain equal number of molecules. This is Avagadros Law.
Q5. For liquid ⇌⇌ vapour equilibrium, at a given temperature, the constant is
Answer : Option B
Explaination / Solution:
The vapour pressure is constant at a given temperature for liquid ⇌ vapour equilibrium. The equilibrium vapour pressure of a compound at a given temperature is an intrinsic property of the compound, meaning it does not depend on variables like volume, quantity of the compound, etc.
Q6. In the alkene having IUPAC name 3-Methyl-1-butene the double bond lies on carbon atom numbered
Answer : Option B
Explaination / Solution:
‘1’ is written before butene which indicates that the position of the double bond is on carbon 1.The structure of the compound is: CH2=CHCH(CH3)CH3
Q7. Formation of coloured solution is possible when metal ion in the compound contains
Answer : Option A
Explaination / Solution:
Color in complex arises due to the presence of unpaired electrons in the system when complex reaction takes place.
Q8. The enthalpy change of a chemical reaction equals ( and are stoichiometric coefficients)
Answer : Option A
Explaination / Solution:
Q9. According to IUPAC nomenclature,element Ununnillium have an atomic number of:
Answer : Option A
Explaination / Solution:
un=1 nil=0 So 110 = ununnilium.
Q10. When an electric discharge is passed through gaseous hydrogen, the H2 molecules dissociate and the energetically excited hydrogen atoms produced emit electromagnetic radiation of discrete frequencies. The hydrogen spectrum consists of
Answer : Option B
Explaination / Solution:
The emission spectrum of hydrogen consists of several series of sharp emission lines in the ultraviolet (Lyman series). in the visible (Balmer series). and in the infrared (Paschen series, Brackett series, etc,) regions of the spectrum. These series are named after their discoverer.
