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The main constituent of bio-gas is:

Why a magnesium

ribbon should be cleaned before burning?

what is baking powders formula?

Ammonia reacts with excess of chlorine to form a yellow coloured highly explosive liquid. What is the chemical formula of that liquid?

1) HCL gas do not turn dry blue Litmus to red.give reason.

2) what are the materials required to show that acids reacts with carbonates and hydrogen carbonates to liberate carbon dioxide?

What is the mass of nitrogen in 1000kg of urea, [$CO(N{H}_2{)}_2$]? ( Answer correct to the nearest Kg) [H = 1, C = 12, N = 14, O = 16]

(a) What type of oxides are formed when non-metals react with oxygen ? Explain with an example.
(b) What is the nature of oxides are formed when metals combine with oxygen? Explain with the help of an example.

(a) Why does aluminium not corrode right through?
(b) What is meant by 'Anodising'? Why is it done?

A, B and C are the elements of a Dobereiner’s triad. If the atomic mass of A is 7 and that of C is 39, what should be the atomic mass of B ?

A carbon atom is tetravalent, I.e. it can form four covalent bonds.

Which of the following bonds are possible between two carbon atoms?

Fresh milk has a pH of 6. When it changes into curd (yoghurt), will its pH value increase or decrease? Why?

How to prevent rusting?

Which of the following is the correct name of the compound?

If ammonia gas is mixed with water then will it react with water to form ammoniun hydroxide?

Question:

The Van der Waals radii of O,N,Cl,F and Ne increases in the order?

Chemistry Periodic Properties and Variations of Properties - Physical and Chemical Size of the Atom or Ion

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Solution:

Van der Waals radius decreases along a period from left to right due to increase in nuclear charge and then increases at noble gasses.

Chlorine being the element from the third period and rest from the second period has the largest size.

My question is if the radii at noble gases increases then in the ascending order how is neon placed before fluorine ? Plz explain. Thank you.

How is the concentration of $H_3{O}^{+}$ ions affected when an acid is diluted?

Is a double displacement reaction reversible? If no, why?

What happens when iron is heated with steel.

How to find the valency of an element

What happens when Aluminum metal is added to diluted hydrochloric acis

What are acids?

A metallic oxide which cannot be reduced by coke.

What is the general name of the chemicals which are added to fat and oil containing foods to prevent the development of rancidity ?

Tomato juice will have a pH:

Fill in the blanks with the correct words from the brackets :

Alkenes are the (a) ...... (analogous/homologous) series of (b) ... (saturated/unsaturated) hydrocarbons. They differ from alkanes due to the presence of (c) .... (double/single) bonds. Alkenes mainly undergo (d) (addition/ substitution) reactions.

Name the products formed when hot and concentrated sulphuric acid reacts with the following :

(a) Sulphur, (b) NaOH, (c) Sugar,

(d) Carbon, (e) Copper.

How can we say that a certain has higher electronegativity?

In Copper & Zinc which is more electronegative?

Which type of reaction is this? (Include subcategory if applicable)

Ca(OH)₂ + CO₂ ----> CaCO₃ + H₂O

State the law of conservation of mass.

Which following chemical is used to clean water in a water plant?

Which process is used to reduce aluminium oxide to aluminium?

What is the name of funcctional group -COOH?

Butanone is a four carbon compound with functional group:

Question 12(b)
A milkman adds a very small amount of baking soda to fresh milk.
(b) Why does this milk take a long time to set as curd?

Acids as we know dissolve most of the metals, but its hard dissolve the metals like gold and platinum. Can you name a special mixture of acids which dissolves noble metals like gold?

In the food chain given below, if the amount of energy available at the fourth trophic level is 5 kJ, what was the energy available at the producer level?

$Grass\to Grasshopper\to Frog\to Snake\to Hawk$

(a) 500 kJ (b) 50 kJ (c) 5000 kJ (d) 5 kJ

What percentage of sun's energy falling on the leaves of green plants are utilised by the plants in the process of photosynthesis and stored as chemical energy of food?

(a) 99 per cent (b) 10 per cent (c) 1 per cent (d) 20 per cent

A non-metal X exists in two different forms Y and Z. Y is the hardest natural substance, whereas Z is a good conductor of electricity. Identify X, Y and Z. [3 MARKS]

Which is a better electrolyte Dil. HCl or conc. HCl? Explain

What are the number of possible structural isomers for a hexane.

In the given figure, when temperature is increased then which of the following increases.