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.
The metal is rapidly attacked by fused alkali oxides and by peroxides and will react with fluorine and, at red heat, with chlorine. On heating, platinum combines directly with elemental phosphorus, silicon, lead, arsenic, antimony, sulfur, and selenium, a fact that influences the use of platinum laboratory equipment. In keeping with the other members of the platinum group, the metal shows a fairly strong tendency to form complex ions.