The obligation of zakaat

Q: I am a student dependant to my parents. According to the nisab of silver ($400) I am supposed to pay zakaat. And I didn't know this as I was told that nisab is $3000 (as per gold nisab). So should I pay zakaat? I had $500 saved up for about 2 years. Also I was also told that since I am not earning money and I am dependant and my parents do pay zakat, that I am not supposed to. Could you please elaborate?

Oysters

Q: Are oysters haraam? What about oyster sauce and Chinese and Thai dishes using oyster sauce? What exactly is oyster?

Inheritance

Q: My father past away in 2008. I have four sisters and I am the only son. My mother is still alive. I need to no how do we share inheritance of my father? He left one car and a house. The house they say it's half owned by my mother as my father bought the house and was bonded but now its freed. My mother was married in community of property. I have the car with me. Please advise what do I do and how do I pay my sisters out according to Sharia as my father did not have a will and my mother says she owns half the house.

Car allowance

Q: I am working in a company as an engineer and as per my designation car is allowed for my traveling but my company does not have a car infact they pay me money to hire a rent car for my visit. My question is that if I don't use a rent car and claim rent car bill, will it be halaal or haram. For example, I have to travel from city A to B. I travel it through train which is cheaper but to the company I claim rent for car because as per my designation car is allowed to me for my ease. But I want to save some money so I rather use some cheap transport method and claim rent for car. Kindly also note the this is the environment of my company. All my colleagues do this and if I don't do this, they will whisper against me to the higher management and I have a chance to lose job. Even if I travel by train or some other transport and want to tell this to my company then my colleagues will become angry with me and will speak against me. So kindly answer me keeping in mind my both scenarios. One is that as per my designation, car is allowed to me for my ease and second, the environment of my office.

Polygamy

Q: I am a 29 years old, unmarried, looking for a partner. I am struggling to find someone compatible. However today I was driving home at night and saw an ex-boyfriend of mine who is now married walking to mosque with his son. I offered him a ride to mosque and we ended up talking for some time. He asked why I broke up with him and admitted that he still cared for me. I made a joke out of it. Later on I asked him if he could find me a husband, he said he could not but he asked how I felt about being a second wife. My reply was no because I feel I am too jealous. However, I remember watching one of sister aaminas videos where she said that polygamy is actually a gift to the women. I was wondering if you could please explain this to me as I feel if I understood it better I might be more open to it.