Aim To study the comparative cleaning capacity of a sample of soap in soft and hard water. Apparatus and Chemical Three test tube (20 mL) Dropper Test tube stand three beakers (100 mL) :three glass rod A measuring cylinder (50 mL) A measuring scale Underground water Hard water Distilled water Soap solution Principle Hardness of […]
Periodic Classification Of Elements – Previous Years Questions Write the atomic numbers of two elements ‘X’ and ‘Y’ having electronic configurations 2, 8, 2 and 2, 8, 6 respectively. [CBSE 2014] [1 Marks] State the common characteristics of the following elements:Boron, Silicon, Germanium and Arsenic [CBSE 2020] [1 Marks] An element X with atomic number […]
Periodic Classification of Elements Important Questions “Atomic number of an element is considered to be a more appropriate parameter than its atomic mass for a chemist.” Take the example of element X (atomic number 13) to justify this statement. How many triads did Dobereiner identify from the existing elements during his time ? Give an […]
Periodic Classification of Elements Notes Döbereiner’s triads:- Dobereiner arranged elements with similar properties into groups having three elements each and called those groups triads.When the three elements in a triad were written in the order of increasing atomic masses, the atomic mass of middle element was roughly equal to the average atomic masses of other […]
Carbon and its Compounds Previous Years Questions To prepare soap fat/oil is heated with : ester acid alkali alcohol [CBSE 2017] [1 Mark] Four students recorded the following observation while adding soap in soft water and hard water. Soaps form lather easily in soft water as well as in hard water. Soaps form lather easily […]
Carbon and its Compounds Important Questions a. Complete the following equations:-b. Write the name of the following:-i. CH3CH2COOHii. CH3CH2Brc. Draw the electron dot structure of ethene (C2H4). a. Name the compound CH3CH2OH and identity its functional group.b. Give a chemical test to distinguish between ethanol and ethanoic acid.c. Name the product formed when an organic […]
Carbon And Its Compounds – Notes Covalent compound:- The compound formed by the sharing of electrons between the atoms is known as covalent compound. Difference between covalent compound and ionic/electrovalent compounds:- No. Covalent compounds Ionic/Electrovalent compounds (i) Covalent compounds are formed by the sharing of electrons between atoms. Ionic compounds are formed by the transfer […]
Metal and Non-Metals Important Questions In what forms are metals found in nature? With the help of examples explain how metals react with oxygen, water and dilute acids. Also write chemical equations for the reactions. How is copper obtained from its ore (Cu2S)? Write only the chemical equations. How is copper thus obtained refined? Name […]
Metals And Non-Metals : Previous Years Questions Show the formation of Na2O by the transfer of electrons. [CBSE 2019] [2 Marks] Show the formation of magnesium oxide by the transfer of electrons. [CBSE 2019] [2 Marks] What are ionic compounds ? Why do ionic compounds not conduct electricity in the solid state? [CBSE 2019] [2 […]
Metals and Non-metals Notes Physical properties of metals:- They are solid in state except mercury (liquid). They are malleable i.e., they can be beaten into thin sheet.Gold and silver are most malleable metals. They are ductile i.e., they can be drawn into thin wire.Gold is the most ductile metal. They are good conductors of heat […]
As Term 1 Board Exams for Class 10 & 12 are going to start from November 15th, 2021, Central Board of Secondary Education (CBSE) has released the Class 10, 12 sample papers for CBSE Board Exams 2021-22. The sample papers for all subjects for both Classes 10, 12 have been released for Term I exams. […]
The Jharkhand government today said that the schools in the state will remain closed for now for students below 6th standard. Offline classes have been allowed from Monday for classes 6 to 8 in schools, from 8 am to 12 pm. All colleges will re-open and they will function just like earlier, state Health Minister […]
