Which statements describe how stars are born? Check all that apply. Stars are born in clouds of gas and dust called nebulas. The gas and dust are pulled together by gravity. If the cloud that is pulled together has enough mass, a red giant is formed. The pulled-together cloud collapses and becomes hot and dense. Heat and pressure cause nuclear fusion, which signals the birth of a star.

1.Stars are born in clouds of gas and dust called nebulas.

2.The gas and dust are pulled together by gravity.

4.The pulled-together cloud collapses and becomes hot and dense.

5.Heat and pressure cause nuclear fusion, which signals the birth of a star.

Explanation:

answer: option (b) is the correct answer.

explanation:

a covalent bond is formed by sharing of electrons. whereas polarity arises due to difference in electronegativity of two atoms.

therefore, more is the electronegativity of an atom which combines with the titanium, more readily it will induce a partial positive and negative charge.

thus, out of the given options fluorine is most electronegative and has an incomplete octet. therefore, it will readily combine with titanium to share the electrons and complete its octet.  

aquifers are bounded above and below by impermeable rock. the driving force of groundwater movement in confined aquifers is pressure, rather than gravity.