Periodic Classification of Elements — Science STD 10 — Question

Which new species of the rice have been developed in India?

You are given a dry cell, a torch bulb with holder, wires and crocodile clips. How would you use them to distinguish between samples of metals and non-metals?

Write down the reasons, effects and remedial measures taken for any one disaster seen or heard by you.

(a) What happens when copper reacts with concentrated nitric acid? What is the colour of the gas released during the reaction?
(b) Write its balanced chemical equation.
(c) Write the names of reactants and products.

State the general properties of ionic compounds.

An electric bulb is rated as 10W, 220V. How many of these bulbs can be connected in parallel across the two wires of 220V supply line if the maximum current which can be drawn is 5A?

Read the following paragraph and answer the questions based on it:
If heat is exchanged between a hot and cold object, the temperature of the cold object goes on increasing due to gain of energy and the temperature of the hot object goes on decreasing due to loss of energy.
The change in temperature continues till the temperatures of both the objects attain the same value. In this process, the cold object gains heat energy and the hot object loses heat energy. If the system of both the objects is isolated from the environment by keeping it inside a heat resistant box, then no energy can flow from inside the box or come into the box.

i. Heat is transferred from where to where?
ii. Which principle do we learn about from this process?
iii. How will you state the principle briefly?

What is Debereiner’s law of triads? Explain with the help of one example of a Dobereiner’s triad.