Ashining light casts a horizontal beam through a spacecraft.
which two observers would see this beam of light in the exact same way?
a. an observer inside the spacecraft while the spacecraft is at rest and an observer inside the spacecraft while the spacecraft is moving at a constant velocity
b. an observer inside the spacecraft while the spacecraft is accelerating and an observer inside the spacecraft while the spacecraft is at rest
c. an observer on earth while the spacecraft is at rest and an observer inside the spacecraft while the spacecraft is at rest
d. an observer on earth while the spacecraft is at rest and an observer inside the spacecraft while the spacecraft is moving at a constant velocity

in theory, limestone is composed principally of the compound calcium carbonate - caco3, but in reality this compound is deposited in conditions involving a number of other compounds as impurities so it ends up being a mixture of many compounds.

hope this : -)

tony (lordcaos066)

sry but any answer choices

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."