Only outright cash donations to any approved Institution of a Public Character (IPC) in Singapore can be deducted from the donors' assessable income. You can search if an organisation is an IPC at the top right hand corner of the Charity Portal.
As an individual donor, you should give your name and NRIC/FIN to the approved IPC, which will then send the details to IRAS so that a tax deduction will be automatically included in your assessment.
No. This is not an outright cash donation as you are entitled to some form of benefit, i.e. a chance to win prizes.
As the benefit that comes from attending a charity dinner is treated as having no commercial value (i.e. resale value), double tax deduction on the full amount of $200 (i.e. $400) will be granted to the donor.
As the benefit that comes from the advertising space is treated as having a commercial value, tax deduction on the difference between the amount donated and the price of the advertising space is allowed to the donor.