Salaah

Q: In the aeroplane I think it is very inconvenient firstly for myself, secondly for the passengers and thirdly for the air hostesses if I read namaaz standing, can I read it sitting?

Q: I went to a musjid late, when asr namaaz was over. However, I noticed a second jamaat taking place in the sehen,so I joined it. I got the last rakaat. So after salaam I completed my 3 rakaats. Now, after a few days, I discovered that the jamaat namaaz which took place was by musaafirs, so they read 2 rakaats, and I completed 3 rakaats, what is the condition of my namaaz? 

Q: It takes our imam a bit long to go into sajdah, standing up from sajdah, etc. So what happens, for example, is that after qaumah, as the Imam goes down into sajdah, he says Allahu Akbar, and we also go into sajdah, but some of us reach sajdah before him. Is his and our salaah valid? Should we request him to rather try and do his postures slightly faster? I think it is because of his weight problem.

Q: What should be done if one forgets the number of rakaats completed while reading Salah?

Q: In salaah do I have to recite bismillahirrahmanirraheem before surah fateha? Does this make for the 7 ayats mentioned in quran?

Q: In a maghrib salaah, if I join the jamaat in the third rakat, the next two rakats do I have to recite a surah after surah fatiha? Do I have to sit in tashahud in both the remaining rakats? Similarly, how do I do it in isha if I joined in the last rakat?

Q: During weekdays, I perform Zuhar and Asr on the staircase in the office. So, there is not much convenience and hence I miss out zuhur sunnah salaah on a regular basis. And also I perform Zuhr about one hour before Asr time, so that I do not have to do wudu twice. Please advise.

Q: What is the end time of Fajr salaah? For example, if Sunrise is at 6.35 am, can I perform fajr until 6.30 am?

Q: What is the duration between the end time of Asr salaah and the Maghrib salaah? for example, if maghrib salaah time is 6.45 pm, can i perform asr until 6.30 pm?

Q: My house is about one bus stop away from the mosque, which is about 10 mins walk. So, when I'm home, I do the salaah at home and sometimes go to the mosque. Please advise.