Qualifying Child. To be considered a qualifying child, your grandchild must be under the age of 19 on the last day of the tax year, or if he's a full-time student, under the age of 24.No age restrictions apply, however, if your grandchild is permanently and totally disabled.ualifying Child. To be considered a qualifying child, your grandchild must be under the age of 19 on the last day of the tax year, or if he's a full-time student, under the age of 24.
Platinum-iridium alloy. Platinum-iridium alloys are alloys of the platinum group precious metals platinum and iridium. Typical alloy proportions are 90:10 or 70:30 (Pt:Ir). These have the chemical stability of platinum, but increased hardness. The Vickers hardness of pure platinum is 56 HV while platinum with 50% of iridium can reach over 500 HV.
Silicon, a semi-metal, has been found in the native state on rare occasions as small inclusions in gold. Native metals were prehistoric man's only access to metal, since the process of extracting metals from their ores, smelting, is thought to have been discovered around 6500 BC.However, they could be found only in relatively small amounts, so they could not be used extensively.atural alloys of the platinum group metals include: native osmium (Os,Ir,Ru), rutheniridosmine (Ir,Os,Ru), ruthenium (Ru,Ir), palladium (Pd,Pt), platinum Pt, and rhodium (Rh,Pt). In addition gold, copper, iron, mercury, tin and lead may occur in alloys of this group.