Which of the following describes the contribution of eratosthenes? a. discovery of the geocentric theory b. discovery of a mathematical formula to relate the sides of a right triangle c. calculation of the circumference of the world to within one percent d. calculation of the weight of ships by the amount of water they displaced

The correct answer is option C, calculation of the circumference of the world to within one percent.

Eratosthenes was a mathematician and astronomer from ancient Greece. He calculated the circumference of the Earth with reasonable accuracy by noting the position of the Sun’s rays in two different locations.

Eratosthenes believed the Earth was a sphere and used trigonometry and geometry to calculate the distance around Earth.

vanderwaal's forces of attraction are the electrostatic intermolecular forces that exist in a molecule due to the temporary or permanent dipoles that are developed in a molecule. in , the major intermolecular forces are dipole-dipole interactions as the molecule is polar (bent structure). so the vanderwaal's forces of interaction in between molecules are the permanent dipole-dipole interactions that develop due to the dipole that exists in between the polar h - s bond. the positively charged hydrogen atom is attracted towards the negative end of the dipole that is sulfur of the adjacent molecule. therefore, these forces of attraction are relatively stronger than that of london dispersion forces that exist in non polar molecules.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.