I own a warehouse for selling household gas at wholesale prices. Is Zakat obligatory on the empty gas cylinders or only on the liquid gas contents inside the cylinders?

I`m a tradesman and don`t know how to calculate the Zakah due on trading items. Hawl (Zakah year) has lapsed only over some of the goods; some have been damaged and I might return them to the owner. Sometimes, I pay for goods in advance and, sometimes, by installments. I also have money in my bank account, in addition to cash and uncashed checks. Also, people owe me money; some of which are repayable and some are unrepayable. I`m also indebted and have taxes and expenses to pay. I have vehicles, such as cars, trucks and the like, real estate; some are for trade and some aren`t, and some I rent to generate income. This is in addition to my own private money, car and house and other items not set for trade. My wife has also adornment gold, in addition to gold for saving. What is the ruling of Sharia on all of this?

I`m a business agent for some international companies. Customers come and pay, in advance, the price of commodities to be delivered later from the mother company. One full lunar year elapses over the earned amounts. How should I calculate their Zakah?

What is the ruling on giving the Zakah of perfumes as perfumes, and how should their value be assessed? And is it permissible to consult an expert to that end?

What is the ruling of Sharia on the Zakah due on an under-construction real estate?

A company possesses goods, accumulated at the end of the year, that are estimated at (100000) JDs. Its debts are(50000)JDs from the value of these goods. Its net revenues for last year reached(10000) JDs. It owns (30000)JDs that have been deposited in banks for a Hawl(one complete lunar year), and(40000)JDs as cheques under assets. How much Zakah is due on the company in light of these numbers, taking into consideration that its capital is(30000)JDs?

Is the person who invests his money in currency exchange obliged to pay Zakah?

Is Zakaah due on the flats set for sale and rented ones?

I have purchased a plot of land as trade commodity. Once its price goes up, I will sell it. Is it liable for Zakat and when?