CBSE Class 10 - Chemistry - Ch5 - Periodic Classification Of Elements (Concept Points) (#cbseNotes)

PERIODIC CLASSIFICATION OF ELEMENTS (Concept Points)

Modern Periodic Table
credits: By Mbenzdabest (Own work) [CC BY-SA 4.0 ],
via Wikimedia Commons

1. Early chemists classified elements as metals and non-metals on the basis of a set of physical and chemical properties.

2. Dobereiner classified elements on the basis of “Law of Triads” which states that “atomic mass of the middle element of a triad is almost the arithmetic mean of the other two elements”.


3. A triad of elements is a group of three elements arranged in the order of increasing atomic masses, such that a group of such elements have similar physical and chemical properties.


4. Newland classified elements on the basis of “Law of Octaves” stated by him. According to
this law :
“When the elements are arranged in the order of increasing atomic mass, the properties of the eighth element (starting from a given element) are a repetition of the properties of the first element.”

CBSE Class 9 - Biology - Why Do We Fall ill? ( Important Terms to Remember) (#cbseNotes)

Why Do We Fall Ill?  Important Terms to Remember 

Here a few definitions are listed. Can you identify the terms defined here.


Decrease in number of RBCs and heamoglobin concentration.


A condition in which the normal functioning of the body or any part of it is damaged or disturbed.


A rapidly appearing disease, which lasts only in a few days.


A long lasting or a persisting disease.

CBSE Class 8 - Science - Ch 8 - Cell Structure and Functions (Worksheet) (#cbseNotes)

Cell Structure and Functions (Worksheet) 

Fill in the blanks

1. ______ is the structural and functional unit of life.


2. All living organisms are made of ______.


3. Cells were first observed by ____________ in 1665.


4. Antonie van Leeuwen hook was the first to see __________ under microscope which he had constructed himself

CBSE Class 12 - Informatics Practices - Java GUI Programming - Revision Tour-2 (Q & A)

Java GUI Programming - Revision Tour-2
(Q & A)

Questions and Answers

Q: What is Netbeans? Write about its three important features.

Answer: Netbeans is an open source, Integrated Development Environment (IDE) tool for developing Java applications. 

1. Its a RAD (rapid application development) tool that allows us to develop applications by dragging and positioning GUI components from a palette onto a container.

2. Its GUI builder automatically takes care of the correct spacing and alignment of the different components relative to each other.

3. It has in built support for Java Compiler, interpreter and debugger.

4. It has in built text editor with syntax highlighting.

CBSE Class 10 - Chemistry - Chapter 4 - Carbon and its Compounds - Important Points To Memorise (#cbsenotes)

Carbon and its Compounds 

Important Points To Memorise

1. Carbon forms a large variety of compounds because of its tetra-valency and the property of catenation.


2. Hydrocarbons are the compounds of carbon and hydrogen.


3. Hydrocarbons are of two types – saturated hydrocarbons (alkanes) and unsaturated hydrocarbons (alkenes and alkynes)

CBSE Class 8 - General Science - Half Yearly Examination Paper - (2017-18)

CBSE Class 8 - General Science - Half Yearly
Examination Paper - (2017-18)

CBSE Class 9 - Chemistry - Structure Of An Atom, Atoms & Molecules - Practice Test (#cbseNotes)

Chemistry - Structure Of An Atom, Atoms & Molecules - Practice Test

M.M = 40

Q1. What are the failures of Dalton Atomic theory? (3)


Q2. State the law of constant Proportion? verify it for the reaction of 2.047g H₂ and 16.166g O₂ giving 18.210g water.(3)


Q3. How many molecules of water are present in a drop of water which has a mass of 50g? (2)


Q4. Oxygen is (a) Monovalent (b) Bivalent (c) Trivalent (d) Tetravalent        (1)


Q5. Define the terms:
a) Atomic number
b) Mass number       (2)