Answer 1: The Prophet.
Step-by-step explanation: Muhammad is the prophet sent by God for establishment of a monotheistic religion called Islam. Prophet is someone who is chosen among people by God to act as a The Messenger of God in order to bring people to the path of righteousness.
Answer 2: Spain.
Explanation: The conquest of Spain was the beginning of a new era in world history. It was the first time when Islamic civilization interacted with the Latin West. The troops of army were led by Tariq bin Ziyad. Tariq landed on a place called Jabl al Tariq, the mountain of Tariq ( in English Gibraltar), and the straits separating North Africa from Spain are called the Straits of Gibraltar.
Answer 3: The Mongols.
Explanation: In 1251, Möngke Khan was elected the Chief Khan of all Mongols. He launch two expeditions right after his election, one under his brother Kublai Khan to conquer southern China and the other under Hulagu Khan to bring an end to the Caliphate in Baghdad. the Mongols were successful in both expeditions. This victory brought a event of Siege of Baghdad (1258) to become a part of history.
Answer 4: India.
Explanation: Muhammad Al-Khwarizmi was an outstanding Persian mathematician. He was a strong advocate of Hindu numeric system that included number from 1-9 and 0. He said this numeric system had the power and efficiency of revolutionizing the entire Muslim world.
Answer 5: Father-in-law of Prophet Muhammad Abu Bakr became the first caliph after his death.
Explanation: After the demise of Prophet, people felt that the caliphate should be in hands of such a person who has the same potential for becoming a leader as that of Prophet. Abu Bakr was the first man who accepted Islam and was really close friend of Prophet. During last days of Prophet's life, he was chosen by Prophet to lead the prayer for him. He was a man of intellect, thus he was capable of handling a state after the demise of great leader Muhammad.
Answer 6,7,8: As you have asked the same question in last three parts so, i will give an answer for three of them. The answer is that effect of Muslim culture is seen most clearly in Spain, under Islamic rule.
Explanation: If we talk about the linguistic influence we know that Spanish has many words of Arabic origin and it is because of the Arab-Spain relation even before its conquest. Taking entertainment in consideration we see that Spanish music is also influenced by the historic Muslim presence in the peninsula. The instruments and melodies they brought to the region would later give way to the guitar and flamenco. Even the name of the places and many other Arabic culture's foot prints can be seen in Spain.