Physical World

Step 1: Understanding the Term Hypothesis

- A hypothesis is a proposed explanation made on the basis of limited evidence. - It is subject to testing and validation.
Step 2: Why Not Other Options?

- An axiom is a self-evident truth. - A model represents a system but does not imply a supposition. - A postulate is an assumed truth without proof.
Step 3: Conclusion

Since a hypothesis is a supposition without assuming it is true, Option (1) is correct.

Step 1: Understanding the Concept:
There are four fundamental forces in nature. Listed in ascending order of their relative strengths (taking the Strong Nuclear Force as unity, ), they are:

• Gravitational Force ( ):
• Weak Nuclear Force ( ):
• Electromagnetic Force ( ):
• Strong Nuclear Force ( ):

Step 2: Calculating the Ratio:
We need to find the ratio of the strength of the Weak Nuclear Force to the Gravitational Force: Substituting the approximate standard values: Using the laws of exponents ( ):
Step 3: Final Answer:
The ratio is , which corresponds to Option (D).

Strong nuclear force acts between nucleons (protons and neutrons) to hold the nucleus together. It is effective only at very short distances and is stronger than electromagnetic and gravitational forces.

• In decay (positron emission) a proton converts to a neutron, releasing a positron and a neutrino (specifically an electron neutrino, ).
• decay emits an electron and an anti-neutrino.
• Hence the correct answer is (3) Neutrino.