Composition of Matter — Science STD 8 — Question

Carbon contains 6 protons and 6 neutrons. State its atomic number and atomic mass number.

By squeezzing lemon on a piece of rock the gas liberated turned lime water milky. Which compound is present in the rock?

From the symbol 168O, state the electronic configuration of oxygen and the atomic mass number of isotope oxygen.

Which substances are used to clean greenish stains on copper vessels and to shine blackish silver utensils?

A star ends its life as a neutron star when the pressure of its electrons balances its gravity.

Define buoyant force.

Take an empty can. Pour small quantity of water in it. Boil this water for a few minutes until the steam has driven out most of the air. Now close the can with the stopper tightly. Allow it to cool by pouring cold water over it. What do you observe?

If the angle between the plane mirror and the incident ray is 20°, what is the angle between the reflected ray
and the plane mirror?

What are the inclusions in the stroma of chloroplasts?

Which institutes have launched a program to forecast the landslides and its effects?