Give a list of hot objects and cold objects?

What are the different types of Hydrogen Spectral series? The Lyman series of the Hydrogen spectrum lies in the ultraviolet region. Why?

Which one of the following statements is true?

• A. A scalar quantity is the one that is conserved in a process.
• B. A scalar quantity is the one that can never take negative values.
• C. A scalar quantity is the one that does not vary from one point to another in space.
• D. A scalar quantity has the same value for observers with different orientations of the axes.

Which of the following statement is wrong

• A. Young’s modulus for perfectly rigid body is zero
• B. Bulk modulus is defined for solids, liquids and gases
• C. Rubber is less elastic than steel
• D. The stretching of a coil spring is determined by its shear modulus.

Which of the following is incorrect?

• A. All derived quantities may be represented dimensionally in terms of the base quantities.
• B. A base quantity cannot be represented dimensionally in terms of base quantities.
• C. The dimension of a derived quantity is never zero in any base quantity.
• D. The dimension of a base quantity in other base quantities is always zero.

What is time according to Physics?