The correct answer is: They possess high concentrations of free electrons
The main characteristic of good conductors such as metals is the presence of movable electrically charged particles, or electrons. So, when an electric current is applied to a metal, the electrons will move and allow electricity to pass through them. Materials opposite of metals, with low electron mobility are not good conductors, instead they are called insulators.
They are unproven but accepted as fact.
Many experiments support them but they can be disproven by the results of a single experiment. Until then, they stand.
The third statement is correct.
Answer:
143 batteries does Benny need to sample
Explanation:
Given data
confidence level = 97%
error = ±10 hours
standard deviation SD = 55 hours
to find out
how many batteries does Benny need to sample
solution
confidence level is 97%
so a will be 1 - 0.97 = 0.03
the value of Z will be for a 0.03 is 2.17 from standard table
so now we calculate no of sample i.e
no of sample = (Z× SD/ error)²
no of sample = (2.16 × 55 / 10)²
no of sample = 142.44
so 143 batteries does Benny need to sample
Given data:
Volume of calcite (V) = 15 cm³,
mass of calcite (m) = 40.5 g,
find the
density of calcite (ρ) = ?
density is defined as " it is the amount of matter of an object in a given volume". Simply it is the ratio of matter in an object to its volume. The unit of density is kg/m³ in SI system or g/cm³ in CGS system.
Mathematically,
density ( ρ) = mass/volume
= m/V g/cm³
= 40.5 g/15 cm³
= 2.7 g/cm³
Hence, the density of calcite is <em>2.7 g/cm³ </em>
