Coulomb’s law related to electric charges is applicable when of the two charges
d. Both are points
Explanation: Coulomb's law applies specifically to point charges, which are idealized as having no size. It describes the force between two point charges. While it can be extended to spherical charges (considered as point charges at their centers), it is most accurate when both charges are points.
Question ID: 237
Uploaded on: September 22, 2024
The characteristics of a fuse wire are Solution
d. High resistance, low melting point
Explanation:
A fuse wire is designed to protect electrical circuits by melting and breaking the circuit when current exceeds a safe limit. It needs:
Question ID: 238
Uploaded on: September 22, 2024
Present in α - particle
c. Two protons, two neutrons
Explanation:
An α-particle (alpha particle) is essentially a helium nucleus, which consists of:
It has no electrons, making it positively charged. Therefore, the correct composition is two protons and two neutrons.
Question ID: 239
Uploaded on: September 22, 2024
Which of the following is not a periodic property of elements?
d. Radioactivity
Explanation: Periodic properties are characteristics of elements that show a trend across the periodic table, such as density, melting point, and boiling point. Radioactivity, however, is not a periodic property because it does not follow a consistent trend and varies widely among elements, particularly among heavy elements.
Question ID: 240
Uploaded on: September 22, 2024
In which of the following compounds there is no existence of molecules?
b. Calcium oxide
Explanation: Calcium oxide (CaO) is an ionic compound that exists as a lattice structure rather than as discrete molecules. In contrast, hydrogen chloride (HCl), methane (CH4), and ammonia (NH3) are all molecular compounds composed of individual molecules.
Question ID: 241
Uploaded on: September 22, 2024
Which of the following statements is correct in case of electrolysis of CuSO4 solution using Cu electrodes?
d. the concentration of CuSO4 in the solution remains unchanged
Explanation: The correct statement is: the mass of the cathode increases and the mass of the anode decreases. The concentration of CuSO4 in the solution remains unchanged.
Question ID: 242
Uploaded on: September 22, 2024
What colour is produced when H2S gas is passed through an alkaline aqueous solution of sodium nitroprusside?
a. Violet
Explanation:
When H2S gas is passed through an alkaline aqueous solution of sodium nitroprusside, a violet colour is produced. This occurs due to the formation of a complex between sulfide ions and the nitroprusside.
Question ID: 243
Uploaded on: September 22, 2024
The formula of red haematite, an ore of iron, is
b. Fe2O3
Explanation:
The formula for red haematite, an ore of iron, is Fe2O3, which indicates it contains two iron atoms for every three oxygen atoms.
Question ID: 244
Uploaded on: September 22, 2024
By reaction of aqueous NaHCO3 with which of the following compounds CO2 is produced?
d. CH3COOH
Explanation:
When aqueous NaHCO3 (sodium bicarbonate) reacts with acetic acid (CH3COOH), it produces carbon dioxide (CO2) gas. The reaction is:
CH3COOH + NaHCO3 → CH3COONa + H2O+CO2
Question ID: 245
Uploaded on: September 22, 2024
Which fuel gas is harvested from coal bed? OR Name a gas present in the air, the increase in the amount of which causes global warming.
Methane is the fuel gas harvested from coal beds, often referred to as coal-bed methane (CBM).
OR
For the second question: The gas in air that contributes to global warming is Carbon dioxide (CO2).
Question ID: 246
Uploaded on: September 22, 2024
Name an energy source which can be used for sustainable development.
An energy source that can be used for sustainable development is solar energy.
Question ID: 247
Uploaded on: September 22, 2024
Write whether the following statement is true or false : The speed of the gas molecules contained in a closed vessel at fixed temperature and pressure is the same.
False
Explanation:
Even at a fixed temperature and pressure, gas molecules in a closed vessel do not all move at the same speed.
Question ID: 248
Uploaded on: September 22, 2024