Physics

The number 5.400 has four significant figures. All non-zero digits are significant, and trailing zeros after the decimal point are also significant. Therefore, the digits 5, 4, 0, and 0 are all significant, making a total of 4 significant figures. Since the original options did not include 4, the options should be corrected to include 4 as the correct answer.

Incompressible fluid means its density remains constant regardless of pressure changes. This is the defining characteristic of incompressible flow, making option C correct.

Stokes' law applies to small spherical particles moving through a viscous fluid at low Reynolds numbers. The law specifically assumes the particle is spherical to calculate the drag force accurately.

The correct SI symbols for metric prefixes are case-sensitive and must be written directly attached to the unit symbol without spaces. 'mm' (millimeter) and 'km' (kilometer) are correct representations for one-thousandth and one-thousand meters respectively. However, 'um' is incorrect for micrometer; the correct symbol uses the Greek letter 'µ' (mu), so it should be written as 'µm'. Therefore, option C ('1000um') is not a correct representation, making C the correct answer to the question asking for the incorrect representation method.

Alpha particles can excite fluorescence in materials such as ZnS, barium platinocyanide, and calcium tungstate, so all of the listed substances can produce fluorescence when exposed to alpha particles.

The average energy required to remove one nucleon from the nucleus is known as the binding energy per nucleon. This quantity indicates the stability of the nucleus and is a fundamental concept in nuclear physics.

X-rays are commonly used in medical treatments, including skin treatments such as radiotherapy for skin cancers, due to their ability to penetrate tissues and target affected areas. Gamma rays are also used in radiotherapy but are less commonly used specifically for skin treatment compared to X-rays.

The metric prefix 'deca' (also spelled 'deka') represents 10 raised to the power of 1, which means a factor of ten (10¹). This is confirmed by authoritative sources including the National Institute of Standards and Technology (NIST) and the International System of Units (SI) documentation. The symbol for deca is 'da'. Therefore, the correct answer is option A: '10 Raised to power 1'.

In a single encounter, an alpha particle typically loses only a small fraction of its energy because it is a heavy, positively charged particle that interacts weakly with matter over short distances. It does not lose most or all of its energy in one collision.

A smaller least count means the instrument can measure smaller increments, leading to more accurate measurements. Precision relates to the consistency of measurements, not directly to the least count.